Both recently dropped into second, but the clubs have the opportunity to regain some ground when they open a four-game series on Thursday night at Camden Yards. It will be the teams' first meeting of the season after Cleveland took five of seven contests in 2011.
The Indians will be finishing a 10-game road trip, which they have started 1-5, losing five straight. Cleveland is 11-19 and has lost six games in the American League Central standings since May 24, falling 2 1/2 games behind the White Sox.
Cleveland is expected to promote right-hander Zach McAllister from Triple-A Columbus in time to make the start. The club needs a replacement for Jeanmar Gomez, who was demoted to Columbus on Monday.
McAllister (1-1, 3.96 ERA) made four starts for the Indians earlier this season, the last coming on May 23, when he held the Tigers to two runs in 6 2/3 innings. The 24-year-old sports a 22-to-6 strikeout-to-walk ratio in 25 big league innings this season.
"This is not a one-and-done type of thing," manager Manny Acta said. "When Zach came up earlier, he threw the ball well for us."
McAllister made 11 starts for Columbus and posted a 2.98 ERA, 52 strikeouts and 19 walks in 63 1/3 innings.
The Orioles have lost six of eight coming into the series, dropping to five games back of the Yankees in the AL East.
Taiwanese rookie Wei-Yin Chen (7-3, 3.38 ERA) will start for Baltimore. He left his outing on Saturday against the Nationals after giving up three runs in five innings, in part due to a cracked nail he suffered fielding a ground ball.
"Today, I didn't pitch good, and I didn't have good control and good command today, and they [all] found out about it right away," Chen said afterward, through interpreter Tim Lin.
Indians: Choo's southpaw struggles
With Cleveland playing 17 consecutive days heading into the All-Star break, Acta is looking for opportunities to give some of his regulars a rest. That opportunity came Wednesday afternoon for right fielder Shin-Soo Choo.
Part of the reason was that the Indians were facing Yankees lefty Andy Pettitte. Choo's career OPS is more than 200 points lower against lefties than righties, but the gap has widened in 2012. Southpaws have held Choo to an average of .188 (16-for-85) with no home runs.
"He has scuffled a little bit against lefties this year, but he's always hung in there and done decent against them," Acta said. "So I'm expecting that to improve, too."
Chen actually has been tougher on righties this season, holding them to a .698 OPS, compared with .756 for lefties.
The Indians claimed Vinny Rottino off outright waivers from the Mets on Wednesday and designated pitcher Chris Schwinden for assignment.
The 32-year-old Rottino appeared at first base, third base and left field in his 18 games with New York this season, going 6-for-33 (.182) with two home runs and five RBIs. He is expected to be assigned to one of Cleveland's Minor League affiliates.
Orioles: Lack of offense frustrating
The Orioles pounded out 12 runs on 16 hits against the Pirates on June 14, but the offense has struggled in 11 games since.
Over that stretch, Baltimore plated 21 runs on 62 hits, scoring three or fewer runs nine times. The club has notched a total of 15 extra-base hits.
"No one's making excuses in there, we're just frustrated that we're not getting it done," center fielder Adam Jones said after Tuesday's loss to the Angels.
Reliever Troy Patton sports a 1.26 ERA over his last 12 appearances since May 23, striking out 17 while walking two.
The teams split their four games at Camden Yards last season.
The Indians are 17-19 on the road.
Indians outfielder Johnny Damon has played more games (114) at Camden Yards than at any other ballpark where he has only been a visitor. He is hitting .313 there, with an .885 OPS, 21 home runs and 77 RBIs.