Pitching in a pennant race really seems to agree with Mark Prior.

Prior won again, shutting down St. Louis for eight innings Tuesday night as the Chicago Cubs won 7-4 at Busch Stadium.

Two weeks shy of his 23rd birthday and in the midst of his first playoff chase, Prior appeared unaffected by any pressure.

''I'm not trying to go out and strike out 10 guys, I'm not trying to put up a shutout every time,'' he said. ''My job is to keep them from scoring as many runs as we do, and that's the bottom line.''

Prior gave up one run and three hits. He's been dominant since coming off the disabled list from a bruised shoulder, going 5-0 with an 0.69 ERA in five starts.

The Cubs won the opener of a three-game series and stayed within a half-game of NL Central-leading Houston. The Cardinals are one game back, and play Chicago seven more times in the next 10 days.

Randall Simon and Aramis Ramirez hit consecutive homers as the Cubs broke it open with a six-run third inning.

That was plenty for Prior, who struck out six and walked one, he retired 14 of his final 15 batters, with Albert Pujols hitting his 35th home run.

Cardinals leadoff man Kerry Robinson went 0-for-4, not that he was impressed by Prior.

''His fastball is pretty straight,'' Robinson said. ''It's not like he dominated anyone out there. I know he didn't dominate me.''

Giants 3, Rockies 1

Jason Schmidt pitched shutout ball into the eighth inning and San Francisco won at Coors Field.

Colorado hasn't been blanked at home in 354 games, an NL record. That streak was in jeopardy until the Rockies scored when right fielder Jose Cruz Jr. dropped Todd Helton's routine fly.

The Giants have won six of seven since a season-long six-game losing streak. They've won two of three without Barry Bonds, who's been on bereavement leave since his father, Bobby, died Saturday.

Astros 18, Dodgers 4

Jeff Kent homered, doubled and drove in five runs as Houston trounced Los Angeles at Minute Maid Park.

The Astros came within one run of tying the highest-scoring game in franchise history, last done in 1999.

Fred McGriff's 489th career homer gave the Dodgers a 3-0 lead in the first. But Odalis Perez couldn't hold the edge and was tagged for 10 runs and 10 hits in 4 2-3 innings.

Expos 14, Phillies 10

Wil Cordero hit a pair of two-run doubles, helping Montreal overcome an 8-0 deficit at Olympic Stadium.

The Expos still trailed 10-4 before rallying for seven runs in the seventh, with Cordero and Jose Vidro hitting two-run doubles.

Montreal won its third in a row. Ricky Ledee homered twice for Philadelphia, which has lost four straight.

Padres 5, Diamondbacks 4

Phil Nevin and Ryan Klesko hit RBI doubles in the eighth and San Diego rallied past Arizona at Bank One Ballpark.

Down 4-0, the Padres began their comeback on a two-run homer by Gary Matthews Jr. in the seventh. Sean Burroughs added an RBI triple in the eighth.

Before the game, the Padres acquired All-Star outfielder Brian Giles from Pittsburgh for pitcher Oliver Perez, a minor leaguer and a player to be named. San Diego then sent All-Star outfielder Rondell White to Kansas City for a pair of minor leaguers.

Mets 6, Braves 5

Mike Piazza hit a three-run homer and New York won at Turner Field.

Piazza homered against Atlanta for the first time this season. He missed the first 13 games between the teams, sidelined for almost three months with a strained right groin.

Gary Sheffield homered, doubled and singled for the Braves. But their three-game winning streak came to a halt when he grounded out with a runner on first base to end it.

Pirates 4, Marlins 3

Jason Kendall, who hoped to be traded along with Brian Giles to San Diego earlier in the day, hit a two-run homer in the seventh that led Pittsburgh at PNC Park.

Florida lost for the sixth time in seven games, yet stayed tied with Philadelphia in the wild-card race.

Kendall also doubled and singled.