Who will follow Randy Johnson in the marathon race to 300 wins?

Yet when the duo, two of the game's winningest active pitchers, were asked if they had any thoughts about trying to pitch long enough to win 300 games, the mere suggestion was so unfathomable that both men started laughing. "I don't believe so," said Pettitte, who with 220 wins is fourth among active pitchers. "I don't have the desire to do that in my career."

"I don't know about that," said Millwood, who has 146 career wins, tied for ninth on the active list. "I just don't know how many more 300-game winners baseball will see."

That has been a common sentiment as the Big Unit has made his march toward the big unit that is the hallowed 300-win plateau. It's the same refrain that was heard two years ago when Tom Glavine got there, and when Greg Maddux did it in 2004, and Roger Clemens in 2003. The history of baseball suggests that the 300-win club will not be welcoming its last member in Johnson, so the question is not if there will be another, but when, and who? Both questions are almost impossible to answer, but there is already a baker's dozen pitchers worth tracking in the years ahead who may yet reach that milestone.

As of now, there are no likely candidates on the horizon. In fact, for the first time since Nolan Ryan won his 300th in July of 1990, baseball is preparing to witness the initiation of another member in this exclusive fraternity without any reasonable guess as to who the next initiate will be. At that time only four active pitchers had at least 200 wins, and none of them got to 300. Of the four pitchers who would eventually get there, only Clemens with 109 was even a third of the way home (Maddux had 52 wins in his fifth season, Tom Glavine had 29 -- against 35 losses -- in his fourth year and Johnson had 19 in his third).

Now, as Johnson prepares to pull into the 300-win port with no one in his wake, there is a similar dearth of likely 300-game winners. Only three other active pitchers have more than 200 career wins: Philadelphia's Jamie Moyer (250), who is 46 years old and suffering through the roughest season of his career with a 6.75 ERA and a 1.63 WHIP; Pettitte (220), who is pitching well this season as he approaches his 37th birthday in two weeks but said Tuesday, "I'm getting real close to shutting it down. I just made it through May, now I just want to get through June," and John Smoltz (210), Boston's 42-year-old righty who hasn't pitched since last June and is still rehabbing from major shoulder surgery. (Pedro Martinez has 214 wins, and although he hasn't retired he is not on a major-league roster at the moment.)

The list of pitchers between 100 and 200 wins is no more inspiring. That group of 24 is mostly comprised of the ancient (Tim Wakefield, who turns 43 this summer and has 184 wins), the injury-prone (Mike Hampton, 144; Jason Schmidt, 128; Chris Carpenter, 103) and the disappointing (Javier Vazquez, 131; Russ Ortiz, 113).

The most important (and unpredictable) element in the chase will be a pitcher's longevity. At 45 Johnson will be the second-oldest pitcher to reach 300, and his remarkable late-career resurgence -- which includes more wins in his 40s (71 and counting) than in his 20s (64) -- is the biggest reason why. It is that, as much as his fearsome fastball and devastating slider, that are responsible for Johnson reaching this milestone, and anyone wishing to do likewise will need to pitch nearly as well, and almost certainly as long, as Johnson has.

They will also need to have a similar drive to compete. Johnson overcame two back surgeries to keep his Hall of Fame career going strong. Glavine still plans to come back even though elbow and shoulder surgery have kept him from throwing a single major-league pitch since last August. Clemens famously came out of retirement twice (albeit after he had gotten to 300). Pettitte says his longtime friend and teammate urged him to stay in the game and go for 300. "He always talked to me about that, telling me that with the way I worked out I could pitch as long as I wanted," said Pettitte, who has never talked the talk of a guy who's likely to pitch into his 40s, a virtual requirement for those hoping to win 300. In fact, the average age of the 11 300-game winners since World War II when they got their milestone win is 41.2, and only two -- Greg Maddux and Steve Carlton -- were still in their 30s when they did so.

With 299 wins in his 22 seasons, Johnson has averaged 13.6 wins per year. Those numbers are nearly identical to the averages of the 11 pitchers who have won 300 games since World War II. The 23 members of the 300-win club can be broken down into three categories that have each defined the game in its own way: pre-1900, 1900-World War II and post-World War II. The first group had far shorter careers highlighted by astronomical win totals, a product of the rules and style of the game at the time. By the turn of the 20th century, pitchers were beginning to fashion careers of at least two decades, but none of those who got to 300 needed to wait that long to do so. Since World War II, though, as starts per year have dropped, bullpen usage has risen and five-man rotations have come into practice, pitchers have needed to extend their careers into a second decade to get anywhere close to 300, a pursuit aided by increased emphasis and advances in medicine, technology and pitching mechanics.

Using the post-World War II average of 23 seasons, pitchers would have to win a tick over 13 games per year over that time to get to 300. The former is likely to be much more of an impediment than the latter.

Here are the 13 active pitchers with the best chance at 300:

Roy Halladay, Blue Jays, age 32Entering 2009: 131 wins over 11 years (11.9 W/Yr.)Wins needed: 169 over 12 years (14.1 W/Yr.)2009: 9-1 in 12th seasonSkinny: Halladay got off to a slow start with just 18 wins in his first four seasons, but he has made up for it since then. He's already more than halfway to his fourth straight year with at least 16 wins. If healthy he has the best chance of anyone in the game.

Roy Oswalt, Astros, 31Entering '09: 129 wins over eight years (16.1 W/Yr.)Wins Needed: 171 over 15 years (11.4 W/Yr.)'09: 2-2 in ninth seasonA mainstay in the Houston rotation since his 2001 debut, Oswalt has been a workhorse, making at least 32 starts for five straight seasons. He has thrived in the bandbox that is Minute Maid Park, but if he's traded this year, how will a new team and ballpark impact his chances?

Mark Buehrle, White Sox, 30Entering '09: 122 wins over nine years (13.6 W/Yr.)Wins needed: 178 wins over 14 years (12.7 W/Yr.)'09: 6-1 in 10th seasonHe's not glamorous, but he is effective. Buehrle has made 30 or more starts in each of his nine full seasons, and his wins per year is right on target for 300. He has yet to break down or slow down, and without a single 20-win season to his credit, he could be the least-heralded pitcher ever to get to 300.

CC Sabathia, Yankees, 28Entering' 09: 117 wins over eight years (14.6 W/Yr.)Wins needed: 183 over 15 years (12.2 W/Yr.)'09: 5-3 in ninth seasonSabathia's well-noted girth has not kept him from making at least 28 starts in every season of his career, and other hefty lefties, such as David Wells, have managed to pitch for years despite battling weight issues. Sabathia's youth, and the Yankees' willingness to make sure he always has a competitive team around him, will aid his pursuit.

Johan Santana, Mets, 30Entering '09: 109 wins over nine years (12.1 W/Yr.)Wins needed: 184 wins over 13 years (14.2 W/Yr.)'09: 7-3 in 10th seasonSantana won only 11 games in his first three seasons, but he has made up for it since then. He has arguably the best stuff in the game, but with only nine complete games in his career he'll need to rely on his bullpen to help get him to 300. The Mets' 'pen cost him seven wins last season, which might not seem like much but could be damaging over the long haul, and a lack of run support has again plagued him this season.

Carlos Zambrano, Cubs, 28Entering '09: 96 wins over eight seasons (12 W/Yr.)Wins needed: 204 wins over 15 years (13.6 W/Yr.)'09: 3-2 in ninth seasonZambrano's temper, and his sometimes-balky shoulder, are the biggest factors standing in the way of a serious run at 300. He's on pace so far.

Josh Beckett, Red Sox, 29Entering '09: 89 wins over eight years (11.1 W/Yr.)Wins needed: 211 wins over 15 years (14.1 W/Yr.)'09: 5-2 in ninth seasonDidn't win 10 games in a season until his fifth year. Unless he can shake the injury woes that have plagued him (only one season with more than 30 starts), he is a long shot.

Jake Peavy, Padres, 28Entering '09: 86 wins over seven years (12.3 W/Yr.)Wins needed: 214 wins over 16 years (13.4 W/Yr.)'09: 5-6 in eighth season.Peavy's on pace for now, but if he's traded, how will that factor in? Though his ERA has benefited from spacious PETCO Park (and before that, Qualcomm) -- it's more than 1.00 better than on the road -- Peavy has actually won more games away from San Diego than he has in his home ballpark.

Justin Verlander, Tigers, 26Entering '09: 46 wins over four years (11.5 W/Yr.)Wins needed: 254 wins over 19 years (13.4 W/Yr.)'09: 6-2 in fifth seasonWon 35 games in his first two full seasons before taking a step backward last year. Seems to have fixed the problems that plagued him a year ago. Recent history has suggested that power pitchers (Seaver, Ryan, Clemens, Johnson) can get to 300 if they stay in shape, and Verlander falls into that category.

Felix Hernandez, Mariners, 23Entering '09: 39 wins over four years (9.75 W/Yr.)Wins needed: 261 years over 19 years (13.7 W/Yr.)'09: 5-3 in fifth seasonKing Felix debuted at 19, giving him a major headstart on the race to 300, but despite all his wondrous gifts he has had only one winning season in his career. Is he a colossal bust or a clone of Johnson, who was 29 before he had a breakout year? King Felix better not wait that long if he wants to get to 300.

Zack Greinke, Royals, 25Entering '09: 34 wins over five years (6.8 W/Yr.)Wins needed: 266 wins over 18 years (14.8 W/Yr.)'09: 8-1 in sixth seasonGreinke is the story of the year so far, having a breakout season at age 26. Shades of Glavine, who had only 33 wins entering the season he turned 25?

Cole Hamels, Phillies, 25Entering '09: 38 wins over three years (12.7 W/Yr.)Wins needed: 262 wins over 20 years (13.1 W/Yr.)'09: 3-2 in fourth seasonJoining Steve Carlton as lefties who won 300 with the Phillies isn't necessary to endear last year's NLCS and World Series MVP to Philadelphia fans. Hamels has never won more than 15 games in a season, which will need to change if he's to mount any kind of serious charge to make up for inevitable late-career falloff.

Tim Lincecum, Giants, 24Entering '09: 25 wins over two years (12.5 W/Yr.)Wins needed: 275 wins over 21 years (13.1 W/Yr.)'09: 4-1 in third seasonSo young, so good, so far away. Lincecum's crazy windup and superb stuff have baffled hitters, but it's way too soon to know whether he has the staying power to make a serious run at 300.

It isn't yet known whether any of these pitchers will come anywhere close to 300. After all, Dwight Gooden had 154 wins by age 28 and finished with only 194. It may be that it is a pitcher not on this list, or not yet even in the major leagues, who gets to 300 next. The only certainty is, as Pettitte said Tuesday, "After Randy gets it, no one's going to have a shot for a long, long time."