WASHINGTON -- For the first eight weeks of his first season as a Cardinal, Troy Glaus was plenty effective. He played quality defense, got on base, hit doubles and drove in runs. He just didn't do the one thing he was expected to: hit home runs.

But as the weather has heated up, so has Glaus -- and likely not coincidentally, so have the Cardinals. Glaus' third home run in five games propelled St. Louis to a 4-1 win over Washington in the first game of a day-night doubleheader at Nationals Park on Thursday.

Glaus, who hit two homers in his first 55 games as a Cardinal, launched a two-run shot to left-center field in the fourth inning off John Lannan. Ryan Ludwick singled in front of him and stole second base, and Glaus drilled the big fly for a 2-0 Cardinals lead.

"It's nice to hit them, there's no doubt about it," Glaus said. "But I've said it 100 times before: Scoring runs and driving in runs, that's my role in our lineup.

"If it's via the home run, fine. If it's via a two-out single with runners on second and third, that's fine, too. Sure, they're fun. They're great. It was nice to get one. But that's really not the focus of what I was trying to do in that situation."

Albert Pujols added a solo pinch-hit homer in the seventh, and Joe Mather drove in a run with a double, the first extra-base hit of his Major League career. Pujols was held out of the starting lineup due to a strained left calf, but was available to pinch-hit.

"I feel better, but I also understand that he [manager Tony La Russa] prefers not to push it," Pujols said. "If I go out there, he knows that I can be smart, but sometimes I can push it a little bit and be overaggressive. He prefers me to miss one game or two games than miss a whole month, and I prefer that, too."

Todd Wellemeyer breezed through six shutout innings against the struggling Washington offense before he was removed for a pinch-hitter. Wellemeyer acknowledged that hot, humid conditions made the afternoon especially draining.

The right-hander allowed five hits and a walk, striking out five. He needed a mere 79 pitches to record 18 outs, and racked up his seventh straight start with three or fewer earned runs allowed.

"I felt pretty good today," Wellemeyer said. "My two-seamer was moving pretty good. And my slider, I was throwing it where I wanted."

The Cardinals won for the 12th time in 17 games to move a season-best 11 games over .500. They've won the first two games of a nine-game, three-city road trip. St. Louis now trails first-place Chicago by 2 1/2 games in the National League Central.