CLEVELAND (AP) -- Justin Masterson's health is in serious doubt. The Indians' playoff chances are just as iffy.
Masterson was pulled from his start in the second inning with soreness in his left side and Cleveland's hitters stayed in a collective slump Monday night with a 7-2 loss to the Baltimore Orioles, one of the teams the Indians are scrapping with for the AL wild card.
Masterson felt tightness in his side in the first inning, and after applying a heat ointment between innings, Cleveland's All-Star ace took the mound in the second thinking he would be able to continue.
But after a few pitches, his outing was done - and it's possible his season could be over as well.
''It just tightened up on me,'' Masterson (14-10) said. ''I went out to throw and it was like, 'Oh, boy.' I couldn't get through a pitch. I was trying to sink 'em in there, but it wasn't going to work.''
Masterson will undergo an MRI and other tests Tuesday. Those results could determine whether the Indians will continue to battle for one of two playoff spots.
''Hopefully it's nothing serious,'' All-Star second baseman Jason Kipnis said. ''Definitely love to have the big fella out there for us. He's our ace.''
Bud Norris (10-10) stayed unbeaten as a starter with Baltimore and Nate McLouth homered and had three RBIs as the Orioles moved 1 1/2 games ahead of the Indians in the wild-card standings.
Norris allowed one run - a homer to Kipnis in the seventh - and four hits in seven innings. The right-hander improved to 4-0 in seven starts with the Orioles, who acquired him at the July 31 trading deadline from Houston.
Matt Wieters hit a two-run homer in the ninth and Brian Roberts drove in two runs for the Orioles, who didn't take any satisfaction in not having to face Masterson for more than two innings.
''You hate to see that,'' McLouth said. ''I feel really bad for him. He can go through stretches of a game where he's so dominant. It does make a difference.''
Masterson said it's possible he could only miss a few days and that some rest will help. However, he also realizes the tests could reveal something more significant.
''It's not the best-case scenario,'' he said. ''So if it is any more serious than I think it is, we have some good guys in place that can do a lot of work. We're hoping things will be all right. We have a lot of guys coming up who can help out and do a good job.
''I think you're going to see the guys really battle over the next 25 games that we got.
''That's going to show up whether I'm here or not.''
With just one month left, the Indians aren't going to take any chances with Masterson, their leader in wins, innings and just about everything else.
''It's hard to quantify,'' Indians manager Terry Francona said when asked about Masterson's value. ''He's our best pitcher. But when things don't go your way, you can either feel sorry for yourselves or you can find a way to shine. I hope that we are able to come back, whether it takes everybody in the bullpen or guys on the bench, keep fighting.
''That's the best way to do it.''
After dropping two of three in Boston and New York, the Orioles, who staggered through a 12-14 August, arrived in Cleveland needing to string some wins together.
''I knew that schedule was going to be a challenge,'' manager Buck Showalter said before the game. ''We're .500 in our last 10 games. Is it half full or half empty?''
Norris provided some more optimism, striking out eight and keeping his record unblemished in seven starts since joining Baltimore. He allowed just one hit through five innings, and picked Michael Brantley off second in the second.
The Indians are sliding in the wrong direction.
They went 1-5 on a trip to Atlanta and Detroit, only salvaging the finale Sunday thanks to a ninth-inning grand slam by Mike Aviles to beat the Tigers.
Masterson initially showed discomfort while working to Wieters leading off the second. He grimaced and flared his elbow at his side, a motion that sent Francona to the mound accompanied by a trainer.
The right-hander stayed in the game, but after allowing a single to Wieters, he threw an 87 mph fastball to Nick Markakis and paused.
Catcher Carlos Santana headed to the mound and shortstop Asdrubal Cabrera immediately waved toward the dugout, bringing Francona again.
He took the ball from Masterson, who dejectedly walked off the field and then disgustedly tossed a cup of water in the dugout before heading to the clubhouse.
''There wasn't any pull or anything like that that I'm aware of,'' Masterson said. ''We're going to get a few more things checked out over the next couple days.''
Preston Guilmet replaced Masterson and gave up a single to Markakis. With one out, McLouth hit an apparent RBI double to center.
However, the Indians won an appeal that Markakis missed second base, and under rule 10.05, McLouth was not awarded a hit on the play because it was a forceout.
After Guilmet walked No. 9 hitter Alexi Casilla, Roberts hit a two-run double to make it 3-0.
NOTES: Indians RHP Corey Kluber, sidelined since Aug. 6 with a sprained middle finger, will pitch in relief Friday after Scott Kazmir starts against the Mets. Kluber pitched a simulated game Monday, and because he hasn't pitched in some time, the Indians want to be conservative with him. Also, the club is concerned about overworking Kazmir. ''I think it has a chance to help us win, help both pitchers and help the bullpen,'' Francona said. ... Indians OF Ryan Raburn is expected to be activated Tuesday after being sidelined with a pulled calf muscle. ... With his next homer, Hardy will become the fourth active shortstop and ninth since 1901 to record three or more seasons with 25 or more homers.