Lee Mazzilli's pinch-hit single broke a tie as the Pirates rallied for six runs in the third inning and held on to beat New York, 8-7, last night in Pittsburgh.

The Mets fell 4 1/2 games behind the St. Louis Cardinals in the East. The Cardinals were rained out in Montreal and are to make up the game as part of a doubleheader beginning at 3:20 p.m. today.

The Pirates trailed, 5-2, before sending 11 batters to the plate against three pitchers in an inning kept alive by third baseman Howard Johnson's error, which led to four unearned runs.

"That was a tough one," said Mets Manager Davey Johnson. "We couldn't afford to lose it. We need a lot of help now."

"That one hurts," said Keith Hernandez, who had four hits.

After singles by Joe Orsulak and R.J. Reynolds, Sid Bream singled in a run off reliever Tom Gorman. Johnson's error allowed another run to score and Wes Gardner (0-2) walked Sammy Khalifa to make it 5-5.

After Mazzilli singled home a run, Orsulak beat out a roller to pitcher Randy Niemann that allowed two runs to score. It was one of four hits in the game for Orsulak.

"I tried to hit it as hard as I could and ended up barely touching it," Orsulak said. "I don't think he'd have gotten me anyway if he picked it up cleanly. It was like a perfect bunt with great baserunning by Sammy."

"I know that Orsulak has good speed and I didn't think I could field it with my glove, transfer the ball and still get him," Niemann said. "I tried to pick it up with my bare hand and it hit off my little finger. I had to make a choice. I should've eaten it but that never crossed my mind."

The Mets got the first two runners on in the ninth but Jose DeLeon, a 2-18 pitcher, retired Gary Carter, Darryl Strawberry and Tom Paciorek for his second save this season.

"I thought we were going to win it right there," Johnson said.

Larry McWilliams (6-8) won with four shutout innings of relief.

Mets starter Ed Lynch lasted only two innings and 34 pitches before leaving with back spasms.

Dodgers 6, Giants 2: Right-hander Orel Hershiser won his 10th straight game with a four-hitter as Los Angeles stayed 5 1/2 games ahead of Cincinnati and cut its magic number to five by winning at home.

Hershiser (18-3) struck out five and walked two in his fifth win this month.

The Dodgers scored four runs in the second off Vida Blue (7-8). Mike Scioscia singled and took second on a passed ball by Bob Brenly. He scored when Steve Sax singled and took second on the throw to the plate.

A steal by Sax, Hershiser's sacrfice bunt that went for an error, Mariano Duncan's double that brought another error, a steal by Duncan and a groundout produced the other two runs.