While they have clarified their postseason situation by clinching the American League East title and guaranteeing home field advance in the Division Series and League Championship Series, the Yankees nonetheless find themselves in the middle of a race for a playoff berth.

The wild card slot is still up for grabs among two of their AL East competitors, the Red Sox and Rays, and the long-shot Angels of the AL West. The Yankees continued Boston’s September slide with a 6-2 victory in the afternoon portion of the split-bill doubleheader Sunday at Yankee Stadium. The Rays won at home against the Blue Jays to move to a half-game behind the Red Sox in the wild-card standings.

Had the Red Sox lost the night game Sunday, the nine-game lead they held over Tampa Bay Sept. 4 would have completely evaporated. The Red Sox may have saved their season by overcoming a 3-0, first-inning deficit and winning, 7-4, in 14 innings on Jacoby Ellsbury’s third home run of the day to retain their one-game lead for the wild card.

It doesn’t get any easier for the Rays because they have to play the Yankees in their final three games at Tropicana Field while the Red Sox finish up at Baltimore. So the Yankees are still involved in this mix. In the meantime, they are getting a lot of positive vibes about their pitching as they prepare for the postseason. After Freddy Garcia pitched six shutout innings Saturday, A.J. Burnett turned in his best performance in more than two months in the Sunday matinee.

The Stadium crowd of 49,541 bestowed a standing ovation on Burnett as he left the mound with two out in the eighth inning after limiting the Red Sox to two runs and five hits – two of them home runs by Ellsbury, who had three of the hits off the righthander. Burnett walked two batters and struck out six and for a nice change of pace he did not hit a batter, throw a wild pitch or allow a stolen base.

This was an A.J. Burnett start out of 2009, his first season in pinstripes when he was 13-9. His curve was a huge weapon Sunday as Burnett got his record back to .500 at 11-11. It was only his third victory in 15 starts since June 29 but his second straight winning decision. The timing could not be better.

CC Sabathia, who threw a simulated game Sunday and declared himself ready to go, will start Game 1 of the ALDS Friday night at the Stadium against an opponent yet unknown. Yankees manager Joe Girardi has yet to reveal his postseason rotation but Sabathia in Game 1 is a given.

It is also expected that Ivan Nova, Sunday night’s starter who pitched 6 1/3 innings and got a no-decision, will get the ball in Game 2, although that is not a certainty. Burnett and Garcia are in a competition for the other postseason starting assignments with Bartolo Colon and Phil Hughes, who will make their cases in the Tampa Bay series.

The Yankees solved Tim Wakefield’s knuckleball Sunday behind veterans Derek Jeter and Jorge Posada. Brett Gardner and Jeter, who bunted for hits in the first inning, each scored without a hit. Gardner came home on an error by catcher Jarrod Saltalamacchia and Jeter on a wild pitch to put the Red Sox in an early, 2-0 hole.

Posada, batting cleanup for the first time since 2009, hit his fourth career homer off Wakefield, a two-run shot in the third. The crowd ate it up, and Jorgie responded with a curtain call. What a far cry from that May 14 Yanks-Red Sox game when Posada objected to batting ninth and asked out of the lineup. Talk about ancient history.

Jeter added two more hits, a single and a double, that brought his batting average to .300 for the first time since after the second game of the season when he was at .333 on 2-for-6. Jeter was batting .260 when he came off the disabled list July 4. He has hit .338 since then. As late as Aug. 10, the Captain was hitting .271. Over his past 37 games, he has batted .372. DJ got to .299 twice late last month but dipped as low as .292 Sept. 17. Jeter’s current hot streak covers six games in which he has 11-for-22 (.500) with 2 doubles, 1 home run and 4 RBI.

The Yankees’ clinching gives Girardi a chance to rest regulars and give youngsters a chance to get some major-league experience. Perhaps the most pleasant aspect in that regard Sunday was the defensive work at first base by Brandon Laird, who made several sparking plays.

In the nightcap, the Yankees got outstanding relief work until Scott Proctor came on in the 14th and gave up a hit and a walk before Ellsbury connected. Unfortunately, the Red Sox bullpen had an even better night as they held the Yankees to one hit over eight shutout innings.

It was another extra-inning loss for the Yankees, who are 4-11 when going past the ninth, the worst record in the league and the third worst in franchise history, trailing only the 1-9 record of 1933 and the 3-9 of 1949.

The Yankees finished the home season with a 52-29 mark, tied with the Rangers for the best in the AL. The regular-season attendance of 3,653,380 and average of 45,107 per game led the AL, which marked the ninth consecutive season that the Yankees have drawn the most fans at home. This year’s 20 sellouts were the most in the three-year history of the current Stadium.