MIAMI GARDENS, Fla. (AP) The top-ranked Clemson Tigers are undefeated, and they've even beaten the law of averages.
That adage about winning the turnover battle to win the game? It doesn't apply where the Tigers are concerned. They're a minus-two in turnover differential heading into Thursday night's Orange Bowl national semifinal game against No. 4 Oklahoma.
No national championship team in at least 20 seasons has had a negative turnover differential, according to STATS. But Clemson (13-0) has had more turnovers than the opposition in six of its wins.
Coach Dabo Swinney can only scratch his head, and then some.
''I'll probably not have any player play on another team that loses the turnover margin six times and is undefeated,'' Swinney said. ''I've never been a part of that. So yeah, that makes you pull your hair out as a coach, but the positive is we don't have to play perfect to win.''
The Sooners (11-1) are plus-10 in turnovers, a more typical differential for a championship-caliber team. They were minus-one in their lone loss, to Texas in October.
When the teams met in the Russell Athletic Bowl last season, takeaways were the difference, and Clemson won 40-6.
''Turnover margin will be huge in this game,'' Swinney said. ''It was big last year. They had five turnovers, we had none, and that's why the game was the way it was.''
Here are other factors that could swing the semifinal:
The case for Oklahoma
If the Sooners can hold onto the ball better than they did against Clemson a year ago, they'll be tough to stop. They're averaging nearly 46 points per game to rank third in the nation, and also rank third in passing efficiency thanks to Baker Mayfield, who threw 35 touchdown passes and only five interceptions. Other threats in their balanced attack include running backs Samaje Perine and Joe Mixon, and receiver Sterling Shepard.
Unlike Clemson, Oklahoma has lost a game. But the Sooners have outscored opponents by an average of 52-19 in seven victories since their loss to Texas.
''We continued to evolve and grow as a team,'' coach Bob Stoops said. ''Some younger players improved, matured and started to perform at a higher level. As coaches we settled down on some things, and improved in some ways in what we were trying to do.''
The problem with Oklahoma
The Sooners start freshmen at both tackle spots, which is one reason their running game sputtered early in the season. They averaged 3.8 yards per rush in the first six games, and have averaged 6.4 in the past six.
There are also doubts about the defense. The Sooners mount a strong pass rush and have playmakers in the secondary, but they allowed 38, 34 and 29 points in victories and ranked only 46th in run defense, giving up 149 yards per game.
The case for Clemson
Clemson can draw on lots of bowl experience, with a postseason victory each of the past three seasons.
The Tigers' rout of Oklahoma last season is a big argument in their favor. The Sooners' alibi was that they went into the bowl game bummed not to be playing for bigger stakes.
''They didn't want to be there is what everyone says,'' Clemson guard Eric Mac Lain said. ''I don't want to hear that excuse ever again.''
The Tigers' defense was often dominant this year, and their offense is tough to stop because it is so balanced - 30 touchdowns rushing, 30 passing. Heisman finalist Deshaun Watson has thrown for 3,512 yards and run for 887.
The problem with Clemson
Depth was depleted when Swinney sent three backups home Tuesday for breaking team rules, including speedy receiver Deon Cain, who is second on the team with 582 yards receiving.
The Tigers' defense ranked seventh in the nation, allowing 295.7 yards per game, but they've given up 69 points in the past two games. And then there are those pesky turnovers - Watson has thrown 11 interceptions, and Clemson has lost the ball 25 times, which tied for 107th in the nation.
Clemson has overcome such mistakes, but they can make all the difference now that the season has been whittled down to the final four.
''You're splitting hairs here,'' Swinney said. ''These are four great teams, and that's going to come down to a few plays. We're just trying to make sure we're the team that makes those plays.''
AP College Football website: http://www.collegefootball.ap.org