OAKLAND, Calif. -- Left-hander Cole Hamels and right-hander Yu Darvish were struggling before pitching gems in the first two games of the Texas Rangers' three-game series against the Oakland A's.

Hamels pitched seven shutout innings in a 3-0 victory on Friday night when the Rangers clinched the American League West title. Darvish blanked the A's for seven inning in a 5-0 win on Saturday afternoon.

Both pitchers got back on track in what were likely their next-to-last starts before the postseason begins.

On Sunday, right-hander Colby Lewis will try to regain his pitching groove when the Rangers go for a series sweep at the Oakland Coliseum.

"He's a real important guy on our team, too," Rangers shortstop Elvis Andrus said of Lewis after hitting a pair of two-run homers. "He carried our team in the first half."

Lewis will make his third start since returning from a two-month stint on the disabled list with a strained lat muscle in the back of his pitching shoulder. Lewis went 0-2 with a 5.06 ERA in his past two starts. In his last start, he gave up three runs and three hits in 5 1/3 innings in a 6-3 loss to the A's.

Lewis is 12-5 with a 2.87 ERA in 29 games, including 27 starts, in his career against Oakland. He has more career wins and starts against the A's than any other team.

In his last start at the Coliseum on June 16, Lewis took a no-hitter into the ninth inning and settled for a two-hit shutout in a 6-0 victory. He improved to 6-0 with that win but has lost his past three starts.

A's rookie right-hander Jharel Cotton will make his fourth career major-league start and try to pitch his fourth straight gem. He's 1-0 with a 1.50 ERA and has allowed one earned run in each of his three starts.

"It's been good," Cotton said. "My confidence is now higher, but the job's not done. I think I have one or two more starts to go and I want to go out there and give my team a chance to win and go out there and pitch the way I know how to pitch and have fun out there on the mound."

Cotton joined John Henry Johnson and Rich Harden as the only pitchers in Oakland history to start their careers with three straight outings of at least five innings and one or fewer earned runs.

A's manager Bob Melvin said what has stood out most about Cotton is the poise he has had from the minute he took the mound in his debut on Sept. 7 in a 4-1 victory over the Los Angeles Angels in Oakland.

"I know he was a little nervous in the bullpen, but once he got on the mound, he looked like he was really comfortable," Melvin said. "He's with a new organization, he's pitching at the big leagues for a first time. There's a lot of things that can unnerve you on the mound, and it didn't look like that was the case with him.

"The stuff you see. The stuff is good, but I think the confidence that he had when he first took the mound probably impressed me the most. He's another guy that definitely we'll take a hard look next year in the rotation."

Cotton is one of three pitchers the A's acquired from the Dodgers earlier this season in exchange for outfielder Josh Reddick and left-hander Rich Hill.