CINCINNATI (AP) -- Jeff Samardzija didn't have a problem breaking a sweat.
Samardzija pitched into the eighth inning on a warm, humid night that was to his liking Wednesday, keeping his fastball around 96 mph the whole way, and the power-challenged Chicago Cubs hit a pair of homers for a 3-1 victory over the Cincinnati Reds .
A warm front moved through the area on Tuesday night, setting off rounds of thunderstorms that forced postponement for the opening game of the series. When Samardzija took the mound a day later, it was 87 degrees for the first pitch.
Perfect for Samardzija (3-1), who grew up in Indiana and is used to heat and humidity.
"It feels nice to have warm weather, I'll tell you that much," he said. "Late in the game, it keeps your arm going. It's amazing what a difference it makes."
The right-hander allowed only three hits in 7 2-3 innings, leaving after giving up a two-out walk. He threw 94 pitches - 60 for strikes - and struck out seven.
Samardzija spent most of his first four seasons in the Cubs bullpen. He won a spot in the rotation during spring training and has pitched well enough to keep it.
"It seems like things keep getting more and more important," he said. "It was important to have a good spring, then important to have the good start. It'll be important to finish strong."
Bryan LaHair and Ian Stewart hit solo homers off Bronson Arroyo (1-1) for only the Cubs' third multihomer game of the season. They managed only nine homers in April, fewest in the majors.
LaHair's leadoff homer in the second gave him six overall. Stewart's was his second. The third baseman also had a nice barehanded play to rob Drew Stubbs of a hit in the fourth.
"I take a lot of pride in my defense," he said. "Making a play for me sometimes tops a hit."
Samardzija contained Jay Bruce , holding the NL's player of the week to a harmless double. Carlos Marmol retired all three batters in the ninth for his second save in four chances, finishing off the combined three-hitter.
The Cubs have had only six save opportunities this season, underscoring their early struggles.
It was the second straight impressive start for Samardzija, who struck out a career-high nine Cardinals in 6 2-3 innings on May 24. He's made 10 career starts in the majors.
"He usually doesn't have that command or control," Reds manager Dusty Baker said. "He was throwing 95-98 at the start and he was still at 95-96 when he left. Tonight wasn't us, it was him."
Bruce went 10 for 21 last week with homers in four straight games. He needed a homer on Wednesday to tie the club record - Ted Kluszewski , Johnny Bench , Ken Griffey Jr. and Adam Dunn all homered in five straight.
Bruce flied out, grounded out and doubled.
LaHair led off the second inning with his sixth of the season off Arroyo, who gave up a club-record 46 homers last season when he pitched with mononucleosis and a sore lower back. He's been better so far this season, giving up only two homers in his four previous starts.
Baker said before the game that Arroyo has been bothered by a sore lower back again. Arroyo got an extra day to rest when the series opener was postponed.
Stewart homered in the fourth inning, matching the Cubs' season high for homers in one game. They put together three singles for another run in the sixth off Arroyo, the run scoring on Geovany Soto 's hit. Arroyo gave up nine hits and a walk in six innings, throwing 99 pitches.
The Reds scored in the fourth when Brandon Phillips got caught in a rundown and extended it long enough to let Joey Votto to cross home plate.
NOTES: The final game of the series will feature two starting pitchers celebrating their birthdays. The Cubs plan to activate RH Ryan Dempster from the 15-day DL, where he's been letting his strained right thigh heal. Dempster turns 35 on Thursday. Cincinnati will start Homer Bailey , who turns 26. ... Tuesday's rainout will likely be made up as part of a doubleheader on Saturday, Aug. 18 during the Cubs' only other visit. ... Arroyo picked Starlin Castro off second base in the first inning. ... Cubs 2B Blake DeWitt made a diving stop and flip to second base to start a slick double play in the fifth. ... The Reds signed former Cubs and A's reliever Michael Wuertz to a minor league deal. He's working out at the team's spring training complex in Arizona.