Updated

Travis Wood has allowed more than three runs in a game once all season and has recorded quality starts in 16 of his 17 starts. Yet the Chicago Cubs' right-hander has not won since May 30 despite being among the NL ERA leaders.

Wood pitched six shutout innings against Oakland while giving only three hits Thursday, but left with the game still scoreless.

Matt Guerrier, making his first appearance with the Cubs since being acquired in a trade from the Los Angeles Dodgers, threw a pretty good pitch in the seventh, too. But it got away from catcher Wellington Castillo, allowing Derek Norris to score from third on a passed ball and sending the Athletics over the Cubs 1-0.

Wood walked one and struck five in recording his third consecutive no-decision. He is winless in six starts despite a 2.58 ERA over that span.

"You have to keep battling every single day," Wood said. "Their guy pitched awesome. He kept us off-balance and off the scoreboard. I have to find a way to win these games. I need to step it up a little more."

Wood retired 12 in a row at one point, leaving the game after throwing 101 pitches.

"It was a shame," Cubs manager Dale Sveum said. "Six shutout innings. He pitched another great ballgame. One little passed ball."

Castillo, catching Guerrier (2-4) for the first time, wasn't sure what to expect from the pitch that got away.

"He made a good pitch," Castillo said. "I just didn't get a good read on it and it went between my legs."

The Cubs had a runner thrown out at the plate in the fourth and put two runners on with two outs in the ninth without taking advantage.

Yoenis Cespedes threw out Starlin Castro trying to score from second on Alfonso Soriano's single to left field. Soriano was later thrown out by Norris attempting to steal second, ending the inning.

Dan Straily (5-2) gave up a hit over seven innings after being recalled from Triple-A Sacramento earlier in the day. He made the start to allow a sore Jarrod Parker to get two extra days of rest. Straily walked three and struck out six.

The A's also had a potential run thrown out on the bases. Against Guerrier, Chris Young singled with one out in the seventh but was caught stealing by Castillo. Norris drew a walk and went to third on Seth Smith's single prior to the passed ball.

Pedro Strop also made his Cubs' debut with a scoreless ninth as the Cubs matched their franchise record for players used before the All-Star break with 41. The Cubs also extended their franchise record by using 23 pitchers before the break.

NOTES: Cubs OF Brian Bogusevic left the game after the top of third inning with left hamstring tightness. ... The Cubs announced that RHP Carlos Villanueva (2-4, 3.45) will start Sunday's game against Pittsburgh, filling the spot vacated when RHP Scott Feldman was traded to the Baltimore Orioles. Villanueva started the year in the rotation, but went to the bullpen when RHP Matt Garza came off the disabled list. ... RHP Jeff Samardija (5-7, 3.34) will take the mound Friday night against the Pirates at Wrigley Field. He's 4-2 with a 1.56 ERA against the Pirates all-time, though just 1-2 against them this year.