The summer hard-court season kicks into high gear next week with the first of two Masters 1000 tournaments ahead of the U.S. Open, which begins on Aug. 25. With the Rogers Cup in Toronto and the Western & Southern Open in Cincinnati on tap for the next two weeks, here's a look at some of the ATP players to watch through the last Grand Slam tournament of 2014. (Click here for women's players to watch.)
Novak Djokovic: The best hard-court player in the game reclaimed the No. 1 ranking after winning Wimbledon. With No. 2 Rafael Nadal unable to defend his titles in Canada and Cincinnati after withdrawing from both events with a right wrist injury, Djokovic has a chance to put some distance between himself and the Spaniard in the rankings. The big tournament to watch is Cincinnati, where a victory would make Djokovic the first player to win all nine Masters tournaments.
Rafael Nadal: Will the wrist injury prevent him from defending his U.S. Open title?
Roger Federer: A healthy and motivated Federer is already in Toronto -- wearing a "Betterer" T-shirt -- preparing for his first Rogers Cup since 2011. He's also entered in Cincinnati. Back up to No. 3 after a finalist appearance at Wimbledon, Federer is seeking his first Masters title since the 2012 Western & Southern Open.
Stan Wawrinka: The Australian Open champion is a tough one to read. He's playing with house money after winning a Grand Slam title and his first ATP Masters 1000 title (Monte Carlo in April) while showing the quality to beat anyone. But having accomplished more than he ever thought he would, all in a four-month span, the 29-year-old Swiss acknowledged at Wimbledon that he's still trying to fit all the pieces of the puzzle -- motivation, goals, expectations -- back together. Maybe the post-Wimbledon break helped settle his mind.
Milos Raonic: His routine loss to Federer at Wimbledon in his first major semifinal didn't sit well with Raonic. He says he's motivated by anger during the hard-court season, which sees him defending 600 points at the Rogers Cup, where he made his first and only ATP Masters 1000 final last year. Raonic was to play his quarterfinal match at the Citi Open in Washington, D.C., on Friday.
Grigor Dimitrov: The No. 9 withdrew from the Citi Open with an illness, but he has a great opportunity to rise. He has just 110 points to defend through the U.S. Open. One thing to note: Before advancing to the semifinals at the Italian Open in May, Dimitrov failed to make it past the third round at the first four Masters tournaments of 2014.
Andy Murray: Murray is dangerously close to falling out of the top 10 for the first time in six years. Ranked 10th, he has 630 points to defend in North America after reaching the fourth round of the Rogers Cup and the quarterfinals of the Western & Southern Open and the U.S. Open last year. It's hard to see Murray's finishing the season outside the top 10, given he has no points to defend in the fall, but having rediscovered his form again after back surgery, resolved his coaching situation and shed the pressure to defend Wimbledon, Murray has no more excuses. He needs to deliver on a good surface for him.
John Isner: The top-ranked American (No. 12) performs best on home soil, so it's no surprise he's scheduled to play every week through the U.S. Open. So far he's defended his title in Atlanta but lost his opening match in Washington. The big tests will come in Cincinnati, where he made the final last year, and the U.S. Open, where he's lost in the third round the last two years.
Ernests Gulbis: The French Open semifinalist was disappointing on grass, winning just one match in two tournaments. He made the quarterfinals in Canada last year but has a modest track record in Cincinnati (where his last main-draw victory was in 2010) and has struggled at the U.S. Open, where he's been eliminated by the second round six consecutive years. His French Open run followed a title in Nice, France, the week before, so getting into the groove during the lead-up tournaments would serve him well for the U.S. Open.
Marin Cilic: He's back in the top 20 and has no points to defend until late October. A top-16 seed at the U.S. Open is within reach if he can find his early-season hard-court form, when he won two titles and appeared in three straight finals.
Feliciano Lopez: The 32-year-old Spaniard put together a stellar grass-court season, with a Queen's Club title, a runner-up finish in Eastbourne and a fourth-round showing at Wimbledon. He's just 6-9 in Canada and only 5-11 in Cincinnati, but if his serve is clicking he can cause problems.
Ivo Karlovic: Since May, the 35-year-old has reached three finals and upset Dimitrov at the French Open, though he lost to Steve Johnson in the third round of the Citi Open. Karlovic is ranked No. 31 after beginning the year at No. 78; the top players would breathe a sigh of relief if he can maintain that ranking and be seeded at the U.S. Open, meaning a seed wouldn't see him before the third round.
Vasek Pospisil: A back injury has kept the 24-year-old Canadian from building on a breakout 2013, when he made three semifinals, including at the Rogers Cup while ranked No. 71. Pospisil is showing signs of a turnaround, though. The world No. 36 upset top-seeded Tomas Berdych at the Citi Open on Thursday, advancing to his third consecutive quarterfinal since winning the Wimbledon doubles title with Jack Sock.
Lleyton Hewitt: The 33-year-old Australian won his second title of the season, the Hall of Fame Tennis Championships, last month, and he's ranked No. 45. Few unseeded players are more dangerous than Hewitt, who opened his season by defeating Federer and Kei Nishikori on hard courts in Brisbane, Australia.
Jack Sock: Questions remain about his fitness and grip-and-rip tactics, but back-to-back semifinals in Newport, R.I., and Atlanta boosted Sock to a career-high No. 60 this week. (He lost to Raonic in the second round of the Citi Open on Wednesday.) The promising singles results -- which Sock will hope to continue in Toronto and Cincinnati after receiving wild cards for both tournaments -- coincide with his instantly successful doubles partnership with Pospisil: After stunning Bob and Mike Bryan in the Wimbledon final, the pair made it 2-for-2 by winning the Atlanta title.
Nick Kyrgios: The 19-year-old Aussie hasn't played since his star-making debut at Wimbledon, where he upset Richard Gasquet and Nadal to advance to his first Slam quarterfinal and climb from No. 144 into the top 70. The spotlight will be on him this summer -- as will the pressure to back it up. He will make his Masters debut at the Rogers Cup, which gave him a wild card.
Bernard Tomic: Tomic will need a wild card to avoid playing U.S. Open qualies because the cutoff date for direct entry came before he won the Claro Open two weeks ago. The Bogota title raised his ranking to No. 70 (he's now 72nd) and offered hope of a turnaround, but Tomic followed that performance with a straight-set loss to Denis Istomin in the second round in D.C. As always, though, Tomic can be a tricky opponent if he's focused and executing.