ST. LOUIS (AP) -- The St. Louis Cardinals just keep flexing their muscles.

Mark McGwire hit his second upper-deck home run in as many days and Placido Polanco had a grand slam as the Cardinals hiked their NL-record April total to 44 homers with a rain-shortened 6-3 victory over the Colorado Rockies on Sunday.

"That's a lot of bombs," manager Tony La Russa said. "It's because so many guys have hit them."

All but one of the Cardinals' 14 position players have homered. Leadoff hitter Fernando Vina is the only player who hasn't gone deep.

The Cardinals broke the previous record of 41 homers set by the 1997 Atlanta Braves with two on Saturday night. They have homered in 15 straight games, two shy of the team record set in 1998, with 34 during the streak.

"You get tired watching those guys run around the bases after one swing," said the Rockies' Larry Walker, who hit his first homer. "But that's what they're doing."

The game was called after 6½ innings following a rain delay of 1 hour, 56 minutes. The game had already been delayed 13 minutes at the start and 44 minutes in the fourth inning.

McGwire's fifth homer, off Scott Karl (0-2), was estimated at 463 feet and left fielder Jeffrey Hammonds never moved as the ball soared overhead. It ended up on the field after striking some vacant seats and Hammonds threw it back into the upper deck as McGwire, who also doubled and singled, rounded the bases.

Polanco, who entered the season with two homers in 133 career games, hit his third this year and first career grand slam to make it 5-0 in the second.

"I hit the weights during the winter," said Polanco, who is batting .406 with seven RBI in 32 at-bats. "I didn't play winter ball so I got a little stronger."

Andy Benes (2-1) struck out nine and allowed three runs in six innings to win his second straight start. His biggest mistake was hanging a curveball against Walker in the sixth.

"Just don't ask me anything about the game," Benes joked, referring to the rain delays. "It was three hours ago and I don't really remember what happened."

Jeff Cirillo added a two-run triple for the Rockies.

Fernando Tatis extended his RBI streak to nine games, with 15 in that stretch, when he tripled in the fifth. Center fielder Brian Hunter overshot the ball when he climbed the wall in an attempt to rob Tatis.

"The wind is blowing in, so the ball didn't carry much today," Tatis said. "I hit it pretty good and I thought I got it, but it stayed inside."

Karl allowed five runs and six hits in four innings.

"I can't pinpoint what's wrong," Karl said. "I don't have much for you today."

Heathcliff Slocumb got the save. He retired the side after Ben Petrick's leadoff double in the seventh chased Benes.

Game notes
The major league record for homers in April is 49 by the Cleveland Indians in 1997. The major league record for any month is 58 by the 1987 Baltimore Orioles, who did it in May. ... Benes also struck out nine April 12 at Houston, and has 25 strikeouts in 22 innings. He has a 20-10 career record at Busch Stadium. ... Colorado's Darren Bragg, who struck out as a pinch hitter, is in a 2-for-21 slump. ... Ray Lankford is the career home run leader in Busch Stadium with 96 in 646 games. McGwire is second with 92 in 190 games. ... Karl is 1-6 with a 6.21 ERA for his career against the Cardinals.