Chicago, IL (SportsNetwork.com) - Andrew Cashner only allowed a pair of unearned runs as the San Diego Padres earned a 5-2 win over the Chicago Cubs on Sunday.

Cashner (1-2) yielded just five hits and two walks in six innings with five strikeouts, and Chicago's two first-inning runs were unearned due to errors by Matt Kemp and Yangervis Solarte.

Will Middlebrooks and Solarte each hit two-run homers in support of the San Diego staff.

Chicago starter Jon Lester (0-2) continued to struggle early in the season. He needed 97 pitches (57 strikes) to get through 5 1/3 innings, allowing three runs on six hits and two walks with four strikeouts.

"I thought he made a lot of progress today," said Cubs manager Joe Maddon. "I think next time out, you should see him beginning to put it all together."

Jorge Soler and Chris Coghlan had RBI hits for the Cubs, and Kris Bryant's double was the first extra-base hit of his career.

After being handed a 2-0 lead in the first inning, Lester faced only two batters before the score was equalized. Derek Norris led off the inning with a single, and Middlebrooks followed by turning on a 1-1 fastball from Lester and sending it into the under-construction bleachers in left field for his third homer of the season.

Maddon has opted to bat the pitcher eighth in every game this season, and that tactic may have cost them a potential rally in the third. With the bases loaded, Lester, who entered the game 0-for-39 in his career at the plate, came up. He promptly struck out and stranded all three runners.

Until the ninth inning, Bryant was the only Cub to reach scoring position after Lester's strikeout.

Meanwhile, San Diego tacked on insurance runs against the Cubs' bullpen. Will Venable, starting in left field with Justin Upton dealing with a strained quad, hit a two-out single to score Kemp in the sixth, and Solarte's two-run homer an inning later accounted for the final margin.

The Padres called on Joaquin Benoit to wrap up the game, and he was on his way to doing so with two quick outs. Chris Denorfia hit a pinch-hit single to keep the game alive, and Dexter Fowler surprised the defense with a bunt single to bring up Soler. Benoit struck out Soler to earn a series win for San Diego.

Chicago struck quickly in the first inning. Fowler singled and advanced to second on Kemp's error, and Soler drove him in with a single. Starlin Castro reached base when Solarte dropped a throw from Clint Barmes that would have ended the inning, and Coghlan singled home Soler.

Game Notes

Chicago has stolen a base in five straight games ... This was the Cubs' first series loss this season ... Coghlan's RBI single was the 500th hit in his major league career ... Padres manager Bud Black was ejected for arguing a strike call in the second inning ... Chicago starts a four-game series at Pittsburgh Monday while San Diego travels to Colorado for four.