OAKLAND -- Few likely would have believed A's manager Bob Melvin when he referred to the Chicago Cubs as a "dangerous" team before Tuesday night's game.

Melvin's straight-faced assessment seemed even more misguided on the heels of the Cubs trading pitcher Scott Feldman and former closer Carlos Marmol earlier Tuesday.

Who's rolling their eyes now? Certainly not the A's after the Cubs rallied from an early deficit, held a lead late and made the A's work hard for their 8-7 victory in front of 17,273 fans.

The A's surged past Texas into first place in the American League West on the strength of a game-deciding home run by Derek Norris in the eighth. This marks the first time the A's held sole possession of the division lead since June 21.

They regained first place by winning at home for the 17th time in 20 games and improving to an A.L.-best 27-13 at the Coliseum, while the Rangers fell to Seattle.

Feldman was slated to start against the A's in the opener of the three-game series Tuesday. Instead, the Cubs went with left-hander Chris Rusin, which prompted Melvin to go with right-handed hitting Norris as his starting catcher.

"They make a trade, throw a lefty instead, we switch the lineup and (Derek's) the hero," first baseman Nate Freiman said. "That was awesome."

Freiman could have been referring to Norris' two-out, three-run homer in the eighth or Norris throwing out Luis Valbuena on the back end of a strike-'em-out, throw-'em-out double play in the ninth.

Melvin said Norris' penchant for coming up big with the outcome in question is something he and Norris' teammates almost expect.

"He does his best work late in games, with runners in scoring position," Melvin said.

Norris entered the game batting only .195. However, Melvin and Norris' teammates are bolstered by past results in tense situations.

"If you're going to get a few hits, obviously the bigger situations are the type of things that get the respect of your teammates and gives us confidence that when he comes up there in big situations, he's going to come through," Melvin said.

Norris connected on a changeup from lefty reliever James Russell. He said he attempted to drive the ball up the middle for a base hit and keep alive the rally. Instead, he got under the ball just enough for it to carry over the fence.

"I thought it was going to go farther than it did," Norris said.

Grant Balfour overcame a shaky ninth for his 20th save in as many opportunities this season.

Again, Norris came up huge when it mattered most. He threw out Valbuena after Starlin Castro swung and missed at a Balfour pitch for the first out of the ninth.

Josh Donaldson gave the A's a 2-0 lead with a home run in the first inning. He also started the winning rally with a leadoff single. Josh Reddick made it possible for Norris to bat in the eighth by working a walk off Russell.

"That's what we do when we're at our best," Melvin said. "We make pitchers work. ... If they make a mistake, a lot of times we take advantage."

  • Jarrod Parker made it through a bullpen session Tuesday without any setback, and he is on track to make his regularly scheduled start Thursday against the Cubs.

  • Catcher John Jaso participated in a full-scale batting practice session Tuesday. Melvin said Jaso might get a start Wednesday as long as he doesn't suffer any lingering effects from his left palm injury. Jaso played only one game since June 20.

  • The Cubs traded Feldman to Baltimore, denying him a chance to pitch in front of family and friends. Feldman, who graduated from Burlingame High and attended College of San Mateo, will start for the Orioles in Chicago against the White Sox on Wednesday. The Cubs recalled Rusin from Triple-A Iowa to start in place of Feldman. Feldman signed a one-year contract with the Cubs in the offseason and went 7-6 with a 3.46 ERA in 15 starts.

  • The A's roughed up Cincinnati's Homer Bailey for six hits, two walks and four runs in Bailey's most-recent start before he no-hit the Giants on Tuesday.

  • The A's signed Nicaraguan shortstop Jesus Lopez for $950,000 and Dominican shortstop Carlos Hiciano for $750,000 on the first day of international signings. The A's used all but $226,000 of their $1.926 million bonus pool allotment for signing international players.

  • Sacramento pitcher Sonny Gray, outfielder Michael Choice and infielder Grant Green were selected to represent the Pacific Coast League in the Triple-A All-Star Game on July 17 at Aces Ballpark in Reno. Gray will be the starting pitcher for the PCL, marking the second straight year that a River Cats player will start for the league. Graham Godfrey got the nod last season.