The A's will directly feel the effect of Colon's 50-game suspension for a positive testosterone test Thursday night against the Rays in a matchup of postseason contenders.
Pushing for its first playoff berth since 2006, Oakland (67-56) received a huge blow Wednesday when Colon became the second Bay Area major leaguer in a week to test positive for testosterone. San Francisco All-Star outfielder Melky Cabrera received a 50-game suspension Aug. 15.
The 39-year-old Colon was 10-9 with a 3.43 ERA in 24 starts and a popular teammate during his first season in Oakland. He will miss the rest of the regular season and 10 postseason contests if the A's qualify. Any remaining games would be served in a future season.
"It's a shock,'' teammate Grant Balfour said. "He's a guy that we're definitely relying on right now. I guess you could say it's bad timing any time, but especially now.''
The A's did not seem phased by the news during Wednesday's 5-1 victory over Minnesota. Coco Crisp had three hits including a homer while Tommy Milone allowed two hits in eight innings to help Oakland win for the sixth time in seven games.
"It is what it is. We certainly don't support the actions, but you have to move forward,'' manager Bob Melvin said of Colon. "You go through things over the course of the season. You have to have a short memory.''
Tyson Ross (2-8, 6.35 ERA) has been recalled from Triple-A Sacramento to start in place of Colon on Thursday. The right-hander has not pitched in the majors since June 28, when he allowed five runs in four innings of a 7-6 loss at Texas, but went 3-1 with a 2.85 ERA in nine starts since being demoted to the minors.
In his only previous start against the Rays on May 4, Ross was tagged for seven runs in 3 1-3 innings of a 7-2 road loss that was the only defeat for the A's in a three-game series at Tampa Bay.
The Rays (69-55) are playing much better ball these days, having won 18 of 24 to move atop the AL wild-card standings and close in on the East-leading New York Yankees. Tampa Bay also took two of three at Oakland from July 30-Aug. 1.
The Rays also won two of three at home against Kansas City this week, taking the finale 5-3 on Wednesday.
"It's a team you don't really want to come in and play because they're coached well, they're managed well, they play the game right," Royals manager Ned Yost said.
Jeff Keppinger had two hits with an RBI and James Shields threw 7 2-3 solid innings Wednesday for Tampa Bay. Keppinger is batting .354 (17 for 48) in his last 14 games, and is 6 for 17 (.353) against the A's in 2012.
Scheduled Rays starter Alex Cobb (7-8, 4.74) had allowed one run in seven innings in each of his previous three outings before yielding eight runs and 12 hits over 2 2-3 frames Saturday against Los Angeles, although Tampa Bay rallied to win 10-8.
The right-hander gave up one run - a homer by Brandon Inge - in seven innings of a 4-1 victory at Oakland on Aug. 1.
Crisp, 3 for 3 versus Cobb, is 9 for 21 (.429) with two homers and nine RBIs in his last five games overall.
This series will conclude Saturday. Both teams will get a rare Sunday off so Tropicana Field can host a party for the Republican National Convention, which begins Monday at the nearby Tampa Bay Times Forum.