Nationals pitcher Stephen Strasburg was dominant early, but faltered after one of Ryan Zimmerman's two errors and suffered his fifth straight loss Saturday afternoon against the Cubs.

Strasburg retired his first 11 batters -- including six by strikeout -- before surrendering a two-run double to opposing starter Edwin Jackson and a two-run single to Anthony Rizzo in the fifth inning. The right-hander permitted four unearned runs and five hits over five innings of work in an 8-2 defeat. He struck out seven and walked two on 95 pitches, 64 for strikes.

"I feel like I'm going out and pitching well. Just not happening on days I pitch right now," Strasburg (1-5) told reporters after his outing. "It's all going to change. It's still early."

Wilson Ramos, who caught Strasburg's game, told reporters that the 24-year-old lost his focus after giving up the two-run double to Edwin Jackson in the fifth.

Strasburg has not won a decision since opening day against the Marlins. He has a 3.10 ERA and a 1.18 WHIP through his first eight starts of the season. He is scheduled to make his next start Thursday at San Diego. He surrendered four runs and seven hits over four innings of work in his lone start against the Padres last season.