BALTIMORE (Ticker) -- The Oakland Athletics did not enjoy spending another marathon day at Camden Yards. But Gil Heredia made a long flight to Seattle more palatable.

The righthander tossed 7 2/3 scoreless innings as the Athletics earned a split of a day-night doubleheader with a 4-0 victory over the Baltimore Orioles.

"He was sharp," Oakland manager Art Howe said. "Just a heck of a job. (We were) 5-1 on this trip. I don't know what else you can ask for. The guys have been playing great ball." Oakland, which begins a crucial four-game series in Seattle on Thursday, stayed one-half game behind Cleveland in the American League wild card race. The Indians regained the wild card lead by sweeping a day-night doubleheader from the Boston Red Sox.

The split left the Athletics three games behind the Mariners in the AL West.

"Do we have to sweep them?," Oakland first baseman Jason Giambi said. "No, but we have to split or win three of four. There are still a lot of games."

It took more than nine hours for Oakland and Baltimore to get in the first game of their scheduled doubleheader on Tuesday. Following two rain delays totaling more than five hours, the contest was not completed until 10:36 p.m. EDT, resulting in the second game being postponed.

Oakland was upset the game was not played Wednesday night and came out flat this afternoon, managing just four hits in a 2-0 loss.

But Heredia (15-11) put the A's back on track, scattering seven hits without a walk. He struck out six before Mike Magnante got the final out in the eighth. Jeff Tam tossed a scoreless ninth.

Scheduled to pitch the second game on Wednesday, Heredia expressed concern that he would not be able to gear himself to go a day later than his normal turn in the rotation. He need not have worried.

"I threw strikes and had good location," Heredia said. "My split-finger fast balls had the right velocity. I was ahead of the hitters. My control was there."

The Orioles had a few opportunities early in the game, but Heredia was especially tough with runners on base. He escaped a jam in the third by getting Jerry Hairston to ground into an inning-ending double play and Delino DeShields could not advance after leading off the fourth with a double.

After Hairston singled with two outs in the eighth, Magnante walked DeShields, putting runners on first and second. But rookie Chris Richard grounded to first.

The Orioles staged a mild threat in the ninth, putting runners on the corners before Tam closed out the win by inducing Eugene Kingsale to ground to second.

Jose Mercedes (12-7) suffered the loss, giving up solo homers to Eric Chavez, Jeremy Giambi and Matt Stairs. He allowed four runs and 10 hits over 6 2/3 innings, also surrendering a run-scoring infield single to Miguel Tejada.

"I thought both teams were groggy in the first game," Stairs said. "Gil won here for us. It was really important."

Mercedes has suffered back-to-back losses after reeling off four straight victories.

"Jose showed good velocity on his fastball and threw strikes," Baltimore manager Mike Hargrove said. "He placed three fastballs in the wrong spot and it wound up hurting him." Jason Giambi drew his 119th walk, setting a franchise record. Sal Bando (1970) and Rickey Henderson (1998) had shared the previous mark.

The Orioles were outscored 50-13 on a 1-6 homestand and once again dropped a season-high 19 games under .500.