NEW YORK – Once Grady Sizemore hit a leadoff home run, the Cleveland Indians were headed to the AL championship series while the New York Yankees were braced for a showdown with their boss.

Paul Byrd and the Indians bullpen closed out New York 6-4 in Game 4 on Monday night, completing another first-round debacle for the Yankees that might cost manager Joe Torre his job.

The Yankees came in streaking, overcoming a 21-29 start to win the AL wild card. But they were done in by poor pitching, an insect invasion and the latest October vanishing act by Alex Rodriguez, whose bat was quiet until a solo home run in the seventh inning.

The pesky Indians, who wasted a three-run lead in Game 3, chased Chien-Ming Wang in the second and burst ahead 4-0. Byrd kept wiggling out of trouble, and Victor Martinez’s two-run single made it 6-1 in the fourth against reliever Mike Mussina.

A day after averting a sweep, New York put runners on in each of the first seven innings. But when it counted, its high-octane offense fell flat once again, with late homers by Rodriguez and Bobby Abreu not enough.

Cleveland moves on to its first ALCS since 1998, opening Friday night at Boston. The Indians were only 2-5 against the Red Sox this season, but will have aces C.C. Sabathia and Fausto Carmona rested for Fenway Park.

The Indians are seeking their first World Series title since 1948. The NL championship series starts Thursday night with Colorado at Arizona.

Bewildered New York opens yet another offseason of turmoil, another October over nearly as soon as it began. All eyes will be on owner George Steinbrenner, who said over the weekend that he did not think he would keep Torre as manager if New York bowed with another early exit.

Torre managed the Yankees to four World Series titles in his first five years and reached the playoffs in all 12 of his seasons. Yet, that might not be enough for Steinbrenner, impatient his team of multimillionaires has gone seven years in a row with no title and hasn’t even gotten past the first round since 2004. If Torre does depart, Don Mattingly and Joe Girardi are the leading candidates to replace him.

Fans chanted Torre’s name when he made two trips to the mound in the eighth inning, handing the ball to Mariano Rivera for perhaps the final time in an era that brought the Yankees success they had not enjoyed since the 1950s.

A disappointed crowd of 56,315 also might have seen Rodriguez in pinstripes for the final time. A likely MVP during the regular season, A-Rod was largely AWOL in the postseason for the third straight year, striking out with two on in the first and again leading off the third.

Rodriguez, who can opt out of his record $252 million, 10-year contract next month, did hit a solo homer off Rafael Perez in the seventh – ending a streak of 57 consecutive postseason at-bats without an RBI since 2004. He finished 4-for-15 in the series.

Rodriguez is not the only one who may depart. Rivera, Jorge Posada, Andy Pettitte and Roger Clemens also aren’t assured of coming back, although the Yankees probably will try to keep some, if not all.

Derek Jeter will be back, of course. But the hero of postseasons past had just one RBI in the series and bounced into three double plays.

Cleveland completed a sorry season for New York’s teams – the Mets swooned with 12 losses in 17 games and missed the playoffs entirely. And with the Los Angeles Angels, Chicago Cubs and Philadelphia Phillies also knocked out in the first round, television ratings could take a dive.

It was 87 degrees at game time – the hottest Oct. 8 ever in New York City – and the Indians applied heat right from the start.

Wang, battered for eight runs in New York’s opening 12-3 loss, was chased after just three outs – the shortest start of the 27-year-old’s short career.

Sizemore homered on the third pitch of the game, hitting a 95 mph fastball with little sink for just his second shot since Aug. 28. Jhonny Peralta lofted a two-RBI single to center.

Cleveland loaded the bases in the second on two singles and a hit batter – the Yankees argued that Kelly Shoppach was fouled off his bunt attempt, but umpires decided it hit a hand. That was it for Wang, whose stats will be besmirched with a 19.06 ERA in this series.