Gary Carter kept the Mets in the game with four RBI last night in New York, then Tim Teufel pinch-hit a grand slam in the 11th inning and the NL East leaders defeated the Philadelphia Phillies, 8-4. Reliever Roger McDowell gained his sixth victory against no defeats.

In the eighth, Carter's second home run of the game and 10th of the season, brought the Mets even, 4-4. He hit a two-run homer in the sixth and singled a run across in the fourth.

Ray Knight led off the 11th with an infield single off Randy Lerch (0-1). Rafael Santana grounded out, advancing Knight. Barry Lyons, batting for McDowell, was walked intentionally and Len Dykstra walked. Tom Hume replaced Lerch, and Teufel, batting for Wally Backman, sent a 2-0 pitch over the left-center fence, his second homer this season and first career grand slam.

McDowell pitched two hitless innings.

*Astros 12, Padres 1: Bob Knepper pitched a four-hitter to become the NL's first 10-game winner and Kevin Bass and Bill Doran hit Houston home runs in San Diego. The Astros have a four-game winning streak; the Padres have lost 12 of 17.

Knepper (10-3) walked none and struck out five in his sixth complete game. He missed a shutout when Terry Kennedy led off the eighth with a homer.

The Astros, who totaled 15 hits, jumped on Dave Dravecky (5-6) for three runs in the first inning, two on Bass' homer.

Houston scored four runs in the fifth, led off by Doran's homer and featuring a two-run triple by Phil Garner, who scored on an error by shortstop Garry Templeton. Five more scored in the eighth inning, highlighted by Billy Hatcher's two-run triple and three Padres errors.

*Pirates 6, Cubs 4: In Pittsburgh, Sid Bream hit a three-run home run and light-hitting shortstop Rafael Belliard drove in three runs in the defeat of Chicago.

With the Cubs leading, 2-1, Barry Bonds doubled to lead off the Pirates' fifth and Joe Orsulak reached when catcher Jody Davis fielded his bunt and failed to throw to either third or first. Bream followed with his eighth homer, into the right field seats off Dennis Eckersley (2-4).

Eckersley, who allowed four runs in six innings, is 0-5 in his career against Pittsburgh.

The 5-foot-6, 145-pound Belliard, raising his batting average to .218, singled a run home with two out in the fourth off Eckersley and lined a two-run, two-out single off George Frazier in the seventh.

"I'm seeing the ball real well at the plate. When men are on base, I'm trying to hit the ball to right field and move the runners up and the ball is falling in," Belliard said.

Ron Cey hit his fourth homer of the season, and the 11th allowed by winner Bob Kipper (2-5) in 11 appearances. The Pirates beat the Cubs for the sixth time in seven meetings.

*Expos 4, Cardinals 2: Tim Wallach drove in three runs and Hubie Brooks had three hits and three runs as Montreal prevailed in St. Louis.

The Expos scored twice with two out in the first inning against Bob Forsch (5-4). Tim Raines singled. Brooks singled on a high chopper to first base. Wallach doubled them home when his grounder hit a seam by third base and skidded past Terry Pendleton down the line.

"Forsch was a little late getting over to cover first on Brooks' bouncer to Jack Clark beyond the base and Vince Coleman in left field didn't back up on the other one Wallach's hit and two runs score and that's the ball game," St. Louis Manager Whitey Herzog said. "It was the same old stuff for us again. There ain't no way we can play worse than the way we're playing. You couldn't try and mess up and do any better."

*Dodgers 1, Reds 0: Los Angeles' Mariano Duncan scored from second base on Bill Madlock's infield out in the bottom of the ninth.

Duncan singled off Cincinnati reliever John Franco (0-2) and Steve Sax sacrificed. After Enos Cabell was walked intentionally, Madlock grounded to third baseman Buddy Bell, who threw to second for the forceout. Ron Oester's throw to Tony Perez at first base was too late to complete the double play. Duncan kept running and slid under the tag of catcher Bo Diaz.

The Reds complained bitterly about the call by umpire Harry Wendelstedt.

*Giants 3, Braves 0: In San Francisco, Vida Blue and Jeff Robinson teamed on a three-hitter, backed by three hits and two RBI from Jeffrey Leonard against Atlanta. Blue (3-3) picked up his 202nd career victory by pitching seven innings and allowing two hits.