HOUSTON -- Once again, the Houston Astros waited to the final day. And once again, they're going to the playoffs.
"That's the Astros' way," Craig Biggio said. "The only way we know how to get it done."
Houston started the season 15-30 and became the first team since the 1914 Boston Braves to make the postseason after falling 15 games under .500.
"This one has to rank up there as maybe the best, coming from a long way back," said Biggio, part of five of the Astros' eight previous playoff teams. "That just tells a lot about the guys in this clubhouse."
Just like last season, when manager Phil Garner replaced Jimy Williams at the All-Star break, the Astros waited until the last day of the regular season to clinch.
Oswalt became the first pitcher since 2001-02 with consecutive 20-win seasons, throwing six innings and driving in a run for the Astros (89-73).
Houston lost the first two games of the weekend series, but avoided a tie with Philadelphia for the wild card, and having to go on the road for a one-game tiebreaker. The Phillies (88-74) won 9-3 at Washington and finished a game back.
"When I thought we were going to take off, we didn't. When I thought we were going to crater, we didn't," said Garner, who preferred to sip the champagne rather than be doused by it during the postgame celebration. "We came down to the last game, and we did what we had to do."
Houston will play at Atlanta starting Wednesday in a rematch of last year's NL Division Series, won by the Astros in five games for their first postseason series victory in eight tries. The Braves were 5-1 against Houston this season, including a four-game sweep in Atlanta.
"We know we have a daunting task," Garner said.
Houston trailed 4-3 when Oswalt (20-12) threw his last pitch in the sixth. The game was tied by time Jeff Bagwell pinch hit for him in the bottom of the inning.
Jason Lane's 26th homer, on the second pitch of the sixth, tied the game at 4-all. That came after the Cubs had scored twice in the top of the inning on several bloop hits.
Adam Everett had a one-out single before Bagwell, limited to pinch-hitting duties since missing 115 games because of shoulder surgery, hit a grounder. Shortstop Neifi Perez's throw to second was wide of the base, allowing Everett to score the go-ahead run and Bagwell to go all the way to third.
"To get 20 is great, but to get to the playoffs is more," said Oswalt, who was interrupted by a champagne shower from Roger Clemens. "We've come a long way, especially the way the team pulled together and started playing."
Bagwell was the last batter faced by Greg Maddux (13-15), who finished with a losing record for the first time since going 6-14 as a rookie for the Cubs in 1987. The four-time NL Cy Young Award winner allowed six runs and 10 hits over 5 1/3 innings.
Brad Lidge worked the ninth for Houston for his 42nd save, his second in a row since his blown save Friday night that cut a two-game lead in half.
Derrek Lee was 0-for-4 but at .335 became the Cubs' first batting champion since Bill Buckner in 1980. He finished with 199 hits -- 99 for extra bases (50 doubles, three triples and 46 home runs).
"I never realized at the start of the year that I could win a batting title, but it's a great accomplishment," Lee said. "I wanted to get No. 200 today, but I just couldn't get any good swings."
Lee missed becoming the first Cub with 200 hits since Ryne Sandberg in 1984s. Lee was on deck when Jose Macias hit a game-ending liner with two on, setting off a celebration that included fireworks and confetti.
"It was hard to watch them celebrate, especially how we came back on a tough Oswalt," Cubs manager Dusty Baker said. "We didn't give it to them. They earned it."
Oswalt finished with the ninth 20-win season in Astros history, joining Joe Niekro (1979-80) as the only Houston pitchers to accomplish the feat twice. Oswalt is the first in the majors with consecutive 20-win seasons since Randy Johnson and Curt Schilling both accomplished the feat in 2001 and 2002 for Arizona.
Still, Oswalt had his troubles Sunday.
With Philadelphia already ahead in its game, Houston got off to a fast start. Biggio hit Maddux's second pitch of the game for a double, and after Willy Taveras had a sacrifice bunt, scored on Morgan Ensberg's single. Mike Lamb also had an RBI single for a 2-0 lead.
Houston went ahead 3-0 on Oswalt's infield RBI single in the fourth, which came after the Cubs intentionally walked Everett with two outs and a runner at third to get to the pitcher's spot. Oswalt hit a grounder deep into the shortstop hotel that Perez backhanded, and beat a strong throw to first.
Michael Barrett led off the Cubs' fifth with his 16th homer, and Matt Murton and Perez followed with consecutive singles. Maddux then bunted the ball right back at Oswalt to start a double play before Corey Patterson's RBI double made it 3-2.
Nomar Garciaparra had a one-out single in the sixth, and Jeromy Burnitz and Michael Barrett followed with bloop hits for a run. Taveras prevented another bloop hit with a diving catch in center, but Perez put the Cubs up 4-3 with another softly hit single.
- Maddux had won at least 15 games every season since his rookie season, matching Cy Young's record with 17 straight 15-win seasons.