The San Francisco Giants maintained their half-game lead in the NL West last night by scoring four runs in the ninth inning of a 5-1 victory over the Reds in rainy Cincinnati.

Pinch hitter Candy Maldonado singled with the bases loaded in the ninth, then Luis Quinones' three-run triple clinched the victory.

Maldonado is hitting .409 as a pinch hitter this season.

Frank Williams (1-0) pitched the final two innings to get the victory, after starter Mike Krukow allowed five hits and one run over the first seven innings. Krukow didn't return to the game after a rain delay.

Reds starter John Denny (5-7) walked Joel Youngblood to start the Giants' ninth and Chili Davis doubled off Denny's leg. Reliever John Franco walked Chris Brown to load the bases.

Expos 3, Pirates 2: Hubie Brooks hit his 14th homer and Jeff Reardon earned his 18th save to enable Montreal to win in Pittsburgh.

Brooks broke his club record for home runs by a shortstop when he hit a 1-1 pitch into the third deck in the third inning against starter Rick Reuschel (4-8), who lost his fourth straight decision.

Joe Hesketh (6-4) won for the sixth time in seven decisions by working the first five innings.

Reardon entered the game with one out in the seventh and runners at second and third. He retired Joe Orsulak and Tony Pena to end the threat and then held Pittsburgh hitless the last 2 2/3 innings.

None of the 14 base runners he inherited this season has scored. "That's the stat I thrive on," he said.

Braves 5, Padres 3: Pinch hitter Terry Harper singled home Ozzie Virgil with the tie-breaking run with two outs in the seventh inning in Atlanta.

With the Padres leading, 2-1, Atlanta scored three runs in the seventh off reliever Lance McCullers (4-2). With one out, Rafael Ramirez was hit by a pitch and Virgil singled to left. One out later, Ted Simmons, batting for starter Zane Smith (6-8), singled home Ramirez and finished McCullers. Harper greeted Gene Walter with a single. When the ball got past left fielder Carmelo Martinez, Simmons scored and Harper went to third.

Smith gave up five hits over seven innings. Paul Assenmacher, Atlanta's third pitcher, got his seventh save despite allowing an RBI single to John Kruk in the ninth.

Mets 5, Cubs 2: In Chicago, Ray Knight's two-run single broke a ninth-inning tie and helped reliever Roger McDowell become the first Met ever to be 7-0.

"I was in the right place at the right time," said McDowell, who gave up one hit in two innings. "It seems like we win a lot of games in the late innings."

Dick Selma (1968), Tom Seaver (1970), Jon Matlack (1972) and Ron Darling (1986) started seasons 6-0 for the Mets. Darling pitched seven innings yesterday before leaving for a pinch hitter.

With the score 2-2, Gary Carter opened the ninth with a single off loser Ray Fontenot (3-3), who also gave up a single to Darryl Strawberry before right-hander Lee Smith relieved. George Foster greeted Smith with another single, loading the bases, bringing up Knight, a right-hander.

Rather than send up Howard Johnson to bat left-handed, Manager Dave Johnson went with Knight, who singled to left.

Astros 6, Dodgers 4: In Houston, Kevin Bass had an RBI double in a three-run first inning, then homered in the seventh.

Rookie Jim Deshaies (5-2) won his fourth straight game, pitching 8 2/3 innings. He allowed nine hits and got his first RBI with a single in the third inning. Aurelio Lopez got the last out for his third save.

Bob Welch (3-6) lost his fifth straight decision.

Jeff Hamilton's sacrifice fly gave the Dodgers a 1-0 lead in the first. The Astros responded with three runs in the bottom of the inning. Bill Doran singled, stole second and scored on Craig Reynolds' single. After Glenn Davis was hit by a pitch, Bass doubled Reynolds home. A walk to Jose Cruz loaded the bases and Davis scored on a walk to John Mizerock.

Phillies 7, Cardinals 4: Ron Roenicke's bases-loaded sacrifice fly highlighted a three-run 10th inning in St. Louis.

Philadelphia loaded the bases with one out in the 10th against Pat Perry (1-2) on a walk to Ronn Reynolds and singles by Steve Jeltz and Luis Aguayo. After Roenicke's fly, Milt Thompson, who has five hits in his last six at-bats, hit a grounder that first baseman Andy Van Slyke caught by diving to his right. But he threw the ball into the first-base dugout, allowing Jeltz and Aguayo to score.

Steve Bedrosian (4-3) pitched two innings for the victory and Tom Hume pitched the 10th for his second save. It was Hume's second save in as many nights.

Bruce Ruffin, 22, the left-hander who replaced Steve Carlton in the Phillies' rotation, allowed three runs on seven hits in 6 1/3 innings.