The southpaw rookie (3-2) took a no-hitter into the fifth inning and finished by tossing seven innings of one-run ball, striking out eight, to give the host Orioles a 5-2 victory and a split in the team's four-game series against the Indians (58-72).
"I thought he pitched great," said Indians manager Eric Wedge. "He was hitting his delivery all day long. He did a great job with his fastball, particularly throwing inside to the right-handers, which is usually something left-handers, especially young left-handers, have issues with."
Wedge was also impressed with how well the rookie battery of Matusz, who made his professional debut this April, and catcher Matt Wieters worked as a unit.
"You're talking about two young kids out there, with him and Wieters, they really worked a good big league ballgame out there," Wedge said. "I was really impressed."
Matusz was given the comfort zone of a 4-0 lead courtesy of a four-run third inning, which was highlighted by a two-run homer by outfielder Felix Pie. Indians fielders contributed to that frame with two errors.
Cleveland starter Justin Masterson (4-6) took the loss, allowing five runs -- four earned -- in 5 2/3 innings of work, walking four while striking out six.
"His stuff is good, but the biggest issue today was his command of his fastball," Wedge said about Masterson. "It was just one inning that hurt us and we were a little sloppy out there defensively. We created an opportunity for them and they took advantage of it. And aside from that, the story was really the arms on the other side."
Indeed, it took until the fifth inning before the Indians even scratched out a hit off Matusz, as Jhonny Peralta's leadoff single broke up the bid for the record books.
The Indians broke up the shutout in the sixth, when Grady Sizemore scorched a one-out triple to center field and came home on a single up the middle from Jamey Carroll to make it 4-1.
The two teams traded runs down the stretch, but the game never got closer than a three-run differential after the Orioles' four-run frame.
Baltimore (54-77) tacked on an insurance run in the sixth on a sacrifice fly from Brian Roberts.
The Indians looked to fight back in the eighth off reliever Danys Baez with a two-out rally, but managed just one run on an RBI single by Shin-Soo Choo. Choo and Carroll each collected two hits on the day.
For Masterson, who came over to the Indians from the Red Sox with two other pitching prospects in the Trade Deadline deal that sent first baseman/catcher Victor Martinez to Boston, the outing marked his fifth consecutive start. He made six starts early this season for Boston, but had been used primarily as a reliever with the Red Sox.
Masterson's start was another piece of the puzzle the Indians are hoping to figure out by the beginning of 2010 -- which role the first Jamaican-born Major League pitcher is best suited for in the long run. Wedge believes it's as a starter and he's committed to keeping the righty in that slot for at least the rest of '09 to see how he develops.
"He has three legitimate pitches, he has the strength and he has a good head on his shoulders," Wedge said. "I see him as an even-keeled guy, which I think is in the best interest of a starting pitcher. I think we just need to keep sending him back out there, and in time, he's going to learn and get better."
Masterson seems to buy into the plan as well, and realizes he'll take his lumps.
"You're constantly learning out there -- every time you're getting a lot of innings, you figure out who you are as a pitcher," Masterson said. "Some things will go in my favor, some won't. That's the game of baseball. That's why it's so much fun to play and keeps bringing guys back. "
Lisa Winston is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.