HOUSTON (AP) – Brad Lidge couldn’t hold onto the lead for the Astros, and now Houston’s lead over Philadelphia is down to one game.

After Lance Berkman hit a go-ahead, two-run homer in the eighth inning, Lidge blew his first save in more than three months, allowing two runs and four hits in a 4-3 loss to the Chicago Cubs on Friday night.

The Cubs, who won the series opener Thursday night, started the ninth with three straight hits off Lidge (4-4), who had converted 24 straight save chances since June 11. After Matt Murton and Jeromy Burnitz had consecutive singles, Michael Barrett doubled off the top of the left-field wall to tie the game at 3-all.

Corey Patterson hit a hard chopper to first, and Berkman gathered the ball and threw home for the first out. But pinch-hitter Todd Walker, playing for the first time since hurting his knee last Sept. 23, got a grounder by Berkman for a single that sent home Barrett with the go-ahead run.

Ryan Dempster worked the ninth for Chicago and allowed a leadoff walk to Brad Ausmus. Charles Gipson sacrificed pinch-runner Chris Burke to second, and Craig Biggio’s grounder moved Burke to third.

Dempster retired pinch-hitter Orlando Palmeiro on a flyout to right for his 33rd save in 35 chances. He has saved 19 straight chances.

Philadelphia (86-74) won 4-3 at Washington on Friday night and is just behind Houston (87-73) in the wild-card race with two games left. If the teams finish Sunday tied, they would meet in a one-game playoff Monday at Philadelphia.

Berkman’s 24th homer – and 11th in September – came with one out but wasn’t enough to keep the Astros from wasting another impressive start by Andy Pettitte.

Roger Clemens (12-8), who skipped his previous turn because of a sore left hamstring, is the scheduled starter for the Astros on Saturday, and Roy Oswalt (19-12) is set to go Sunday.

After Pettitte was lifted for a pinch-hitter in the seventh with the game tied, the Cubs took a 2-1 lead in the eighth off Chad Qualls. Neifi Perez had a two-out infield single, and shortstop Adam Everett bobbled Derrek Lee’s grounder for an error.

Nomar Garciaparra doubled to put the Cubs ahead. Lee was thrown out trying to score after center fielder Willy Taveras, who had bobbled the ball, threw to Everett for the relay to Ausmus, who tagged out the sliding Lee.

Taveras led off the Astros eighth with a single off Roberto Novoa (4-5) and, after Morgan Ensberg fouled out, Berkman hit an opposite-field shot into the left-field stands. His 11 September homers tied the team record set by Richard Hidalgo in 2000.

Pettitte, who missed the Astros postseason run last season because of a torn tendon in left elbow, gave up a run over seven innings.

It was the second start in a row, both against the Cubs, in which Pettitte allowed just one run without a decision, and both were one-run losses. The left-hander had won seven straight starts before then.

Carlos Zambrano allowed a run and four hits over seven innings, but missed out on his 15th victory.

The Astros failed to score after Zambrano loaded the bases with consecutive walks to Ensberg, Berkman and Mike Lamb in the sixth. Jason Lane swung at the first two pitches, then grounded to Perez at shortstop.

Lamb, in the starting lineup against the left-hander, put the Astros ahead 1-0 in the second with his 12th homer.

Chicago tied the game in the sixth when rookie Ryan Theriot, making his second major league start, doubled and scored on a sacrifice fly by Lee, who got his 107th RBI.

Notes: Biggio hit his 603rd career double, 11th on the career list with Cal Ripken Jr. … The Astros had a crowd of 41,304 for their 14th sellout this season, 10 fewer than last season. … Berkman has 25 walks in September, his high for a month in his career.

AP-ES-09-30-05 2256EDT