ST. PETERSBURG, Fla. -- The surging Tampa Bay Rays have discovered a simple formula: It's hard to lose when you don't give up any runs.

Alex Cobb pitched a four-hitter for his first major league shutout and the Rays beat the Oakland Athletics 5-0 on Thursday night to pull within 2½ games of the first-place New York Yankees in the AL East.

Matt Joyce hit a two-run double in a five-run fifth inning against Tyson Ross, hastily called up from the minors to pitch in place of suspended Oakland starter Bartolo Colon.

After the big inning, it was easy for Cobb.

"All the pressure goes away," he said. "You don't have to be fine, you can just go ahead and attack hitters. Once I got up by five, my main thought was to go as deep as I could and make them hit fastballs."

Cobb (8-8) struck out eight and walked two in his second career complete game, both this season. He bounced back from a poor outing against the Los Angeles Angels to win for the fourth time in five starts.

"Nothing worked the last time. And to his credit, he just threw that in the trash can and did this tonight," Rays manager Joe Maddon said.

It was the 14th win in 17 games for the Rays and their seventh shutout since July 19. They have pitched 13 shutouts this season, second-most in the majors behind the Angels (15).

Cobb threw a called third strike past Yoenis Cespedes for the final out. As the Rays poured onto the field for handshakes, a group of starting pitchers jumped together and bumped shoulders in excitement.

Matt Moore banged into Cobb and sent him tumbling onto the mound, minus his cap. Still clutching the ball in his glove, Cobb climbed back to his feet and smiled.

It's the closest the Rays have been to first place since they were 2½ out before games of June 16.

Oakland dropped into a tie with Baltimore and Detroit for the AL's second wild-card spot, 2½ games behind the Rays. The teams finish their three-game series Saturday and get a rare Sunday off because the Republican National Convention begins Monday in Tampa.

The A's did not have a travel day after beating Minnesota at home on Wednesday afternoon. They were shut out for the 15th time this season.

"We just couldn't figure [Cobb] out tonight," manager Bob Melvin said. "He was throwing chase-fastballs to us. Every time we were looking for a fastball he threw a breaking ball, and every time we were looking for a breaking ball he threw a fastball, so he was pretty unpredictable tonight."

Luke Scott also doubled for the Rays in the fifth against Ross (2-9), called up from Triple-A Sacramento when Colon received a 50-game suspension Wednesday for testing positive for testosterone. The Rays batted around in the big inning, which also included RBI singles by Sam Fuld and Evan Longoria.

Ryan Roberts broke the scoreless tie with a sacrifice fly.

Ross, making his first start for the A's since June 28, pitched six-plus innings. He gave up nine hits while striking out six.

He will be sent back to Sacramento to work out of the bullpen, and the A's plan to bring him back up when rosters expand in September.

"Now I've just got to move forward," Ross said. "Learn as much as I can about relieving, and be ready come September. I'm excited about the opportunity. Out of the `pen, I think I have a chance to help this team win some games."

Stephen Drew had two hits for Oakland, including a fourth-inning single that snapped an 0-for-22 slide. It was his first hit for the A's since he was acquired from Arizona in a trade.

Cobb allowed 12 hits and eight earned runs in 2 2/3 innings at Los Angeles on Saturday night, the only time this month a Rays pitcher has given up more than four runs. The Rays came back from an 8-0 deficit to win that game and take Cobb off the hook.

"It's great to see a teammate go out there and come back from struggling and really carry the team like he did tonight," Joyce said. "I'm really happy for him and really proud of him."

Notes

• Moore, scheduled to start Friday night against Jarrod Parker, is 4-0 with a 1.16 ERA in his last five starts.
• Melvin said INF Brandon Inge (sprained right shoulder) is ready to start a minor league rehab assignment with Sacramento.
• Athletics RHP A.J. Griffin (right shoulder) allowed three runs and four hits over 2 1/3 innings in his first rehab start Wednesday night for Sacramento.