HOUSTON - With their season on the line once again, Roy Oswalt wasn’t the ace the Houston Astros needed him to be.

After clinching the wild card on the final day and winning the MVP award in the NL championship series with two dominating performances, Oswalt blew a 4-0 lead in the fifth inning in Game 3 of the World Series on Tuesday night.

Oswalt gave up five runs in a miserable 46-pitch fifth inning against Chicago in the game the White Sox won 7-5 in 14 innings.

“From the very beginning of the game, I knew I didn’t have the stuff I had in my last start,” Oswalt said. “I got through the first four innings on adrenaline.”

The Astros battled back against Chicago’s bullpen to tie it in the eighth on Jason Lane’s RBI double, but couldn’t finish off the White Sox.

Geoff Blum led off the 14th inning for the White Sox with a home run off Ezequiel Astacio, who also allowed a bases-loaded walk. The Astros are in an 0-3 hole, a deficit no team has ever overcome in the World Series.

Oswalt is often overshadowed in the same rotation with Roger Clemens and Andy Pettitte, the former New York Yankees who joined their hometown team two years ago. But Oswalt is the one with consecutive 20-win seasons, after winning 19 games in 2003.

When the Astros needed to win on the final day of the regular season to secure a playoff berth, it was Oswalt who beat the Chicago Cubs.

And Oswalt was undefeated in six previous postseason starts (4-0), and was the MVP of the NL championship series when he bailed out the Astros against St. Louis.

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Twice after Houston losses in the NLCS, Oswalt held the Cardinals to one run over seven innings. The series-ending Game 6 victory came two days after Albert Pujols’ stunning three-run home run with two outs in the ninth gave St. Louis a 5-4 victory, and kept Houston from winning its first NL pennant at home.

In Oswalt’s first World Series start, Houston went up 4-0 after Lane’s leadoff home run in the fourth. At that point, Oswalt had given up only five runs in 25 1-3 innings this postseason.

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Chicago matched that in one inning, which started with Joe Crede’s home run.

“I got in trouble with some pitches that were up,” Oswalt said.

Juan Uribe singled and pitcher Jon Garland struck out before Scott Podsednik, whose ninth-inning home run won Game 2, had a single. Tadahito Iguchi and Jermaine Dye had consecutive RBI singles to get the White Sox to 4-3 before Paul Konerko flew out for the second out.

“Dye’s at-bat was critical. (Oswalt) pitched in a really good sequence, and Dye flipped the ball out in center field,” manager Phil Garner said. “They just got some hits. That’s what they’ve been doing in this series.”

A.J. Pierzynski then had a two-run double to deep center, a ball that rolled up Tal’s Hill — that irregular grassy mound more than 400 feet from home plate.

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By the time Uribe flew out, Oswalt had thrown more pitches than ever before in an inning.

“Typically in this series, what has happened, the story so far, is they’re hammering on our mistakes, and fouling off good pitches,” Garner said. “We’re exactly opposite. That’s why we’re having so much trouble.”

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Oswalt then needed only 10 pitches to get out of the sixth, but was pulled after walking Konerko to start the seventh. When he threw ball four, Oswalt put his head down and Garner headed to the mound to take the ball out of the pitcher’s hand after 113 pitches.

It was the most runs Oswalt had allowed at home since St. Louis scored six against him on opening day this year. In his 38 previous starts this year, including the postseason, he had given up more than four runs just three times, the last Aug. 27 when the Los Angeles Dodgers got seven off him in an 8-3 victory.