PITTSBURGH (AP) -- Moises Alou and Jason Kendall got all the attention as they came back from serious injuries. Richard Hidalgo got all the RBI.

Hidalgo, back after missing the final two months of last season with a knee injury, hit a grand slam and drove in all of Houston's runs in a 5-2, rain-delayed opening-night victory Tuesday over the Pittsburgh Pirates.

Alou, out last season with an even more serious knee injury, was one of three Astros walked by Jason Schmidt (0-1) ahead of Hidalgo's drive in the sixth -- the first opening-day slam in Astros history. It also was the first grand slam of Hidalgo's career.

Hidalgo probably couldn't wait to get back and face Schmidt, since he is 7-for-11 with three homers against him.

"I'm just happy because that's my first grand slam and because we won. That's the way you want to start," Hidalgo said.

Shane Reynolds (1-0), reluctantly making his fifth consecutive opening-day start for the three-time defending NL Central champion Astros, pitched seven effective innings to outduel Schmidt, whose 1.16 spring ERA led all major league starters.

Reynolds doesn't especially like matching up against the other team's No. 1 starter on opening day. But he shrugged off a whipping wind and temperatures in the 30s to improve to 3-1 with one no-decision in openers.

Reynolds, 10-4 against Pittsburgh, allowed two runs and six hits in seven innings.

"I went completely away from my game, really, the ball felt so slick, my split-finger pitch wasn't there because it was so cold," Reynolds said. "I threw some good ones, but I didn't throw as many as I usually do, not even close."

Reynolds gave up four singles in the first three innings, then settled down to retire 12 of the next 13 batters in sending the Pirates to their seventh consecutive home opener loss.

"On cold nights, the pitcher has an advantage," Astros manager Larry Dierker said. "But to start the season on the road, and to have to wait around an extra day, and have all those emotions, I could see Shane having some of the same problems that Schmidt did. But he didn't."

John Vander Wal broke up Reynolds' bid for his eighth career shutout with a two-run pinch-homer in his first Pirates at-bat in the seventh. Vander Wal's shot was his 14th career pinch-homer.

Doug Henry pitched a scoreless eighth and Billy Wagner, unable to pitch in the final two games of the Astros' playoff series last season because of a sore elbow, finished for the save.

Schmidt, 0-8 in 10 starts against Houston, allowed three hits in six-plus innings, but never did find his control, throwing only 55 strikes among his 98 pitches. He walked six, four of whom scored, with Ken Caminiti drawing a leadoff walk in the second ahead of Hidalgo's one-out RBI double in his first post-injury at-bat.

Asked about Hidalgo's success against him, Schmidt said, "If I knew why, he probably wouldn't hit me that well."

Craig Biggio walked leading off the sixth and, in-between a pair of flyouts, Jeff Bagwell and Alou walked. Schmidt then fell behind in the count 3-1 before Hidalgo hit a drive deep into the nearly empty left-field seats.

"With the count 3-1 and the bases loaded, I've got to come at the guy," Schmidt said. "But he's real good in those situations."

Those left-seats seats -- and nearly all the team-record 54,399 seats the Pirates sold for their last opening day in Three Rivers Stadium -- were filled for Monday's rained-out game. But there were nearly 40,000 no-shows Tuesday, as only 14,610 returned on a raw, wet night.

About a half hour after the game ended, snow flurries whipped through the stadium.

"It was c-o-l-d," Vander Wal said.

Not long after Grammy award winner Christina Aguilera ignored the cold to sing the national anthem in a Pirates jersey and a midriff-baring top, the Pirates began giving away coffee and hot chocolate.

Alou went 1-for-3 with a run scored in his first game since Game 4 of the 1998 NL playoffs. Kendall, the Pirates catcher, was 0-for-3 in his first game since dislocating his right ankle in a frightening accident on July 4.

"I had goosebumps, I really did," Kendall said, and not because of the cold. "I was a little anxious, and probably threw away some at-bats, but it was good to get the first one out of the way."

Astros center fielder Roger Cedeno, obtained from the Mets in the Mike Hampton trade, was a late scratch due to a sore elbow, but struck out as a pinch-hitter in the ninth inning. His replacement, Bill Spiers, threw out rookie Chad Hermansen at the plate in the second inning.

Game notes
Bill Mazeroski, who missed by one vote in February of making the Hall of Fame, threw out the first pitch. Mazeroski and Kendall drew the loudest pregame cheers. ... The Astros' four-run sixth was delayed for about five minutes as stadium workers repaired a piece of protective padding in front of a home-plate level box seat. ... The Pirates will move across the street into PNC Park next season. More than 200 construction workers employed at the new stadium site were given tickets to the opener. ... . Vander Wal's homer was the Pirates' first on opening day since Jay Bell's drive in 1995. ... The Pirates have been outscored 51-16 in their last seven home openers.