BRADENTON, Fla. - The Baltimore Orioles starting rotation is all but set. The competition was finished as soon as it was announced on Saturday that Jake Arrieta would pitch a minor league game on Tuesday, keeping him away from the Minnesota Twins, who he would face in the fifth game on Apr. 6.

On Sunday, manager Buck Showalter denied that the rotation was complete. Arrieta hasn't been designated as the fifth starter yet, he said.

"We haven't gotten there yet," Showalter said. "I'm not precluding him from being in the mix."

Jason Hammel and Wei-Yin Chen will probably be the first two starters. Miguel Gonzalez is likely to start the home opener on Apr. 5. Chris Tillman, who pitched a minor league intrasquad game on Sunday morning, will probably be the third starter.

Tillman missed a start because of abdominal soreness, and the Orioles want to make sure that he has enough stamina to be the third starter.

One who probably won't be in the rotation is Brian Matusz, who was staked to an 8-0 lead before he took the mound. He managed to allow five runs and nine hits in four innings.

"As a starter, that's a great thing to have, to get eight runs in the top of the first. Went out there, never found a rhythm and didn't pitch well. Was able to get my work in, throw pitches, and be able to use all four pitches, but I was leaving the ball up in the zone. They were hitting them," Matusz said.

In the first inning, the Orioles scored eight runs and sent 12 batters to the plate. The offensive highlight was Chris Dickerson's grand-slam home run.

The Orioles ended up beating the Pittsburgh Pirates 12-10 before 6,528 at McKechnie Field.

Troy Patton had a horrible outing, too. He allowed five runs to allow Pittsburgh to tie the game in the sixth at 10-all.

"It's one of those spring training days where it was a tough for everybody," manager Buck Showalter said.

Matusz said a quicker first inning wouldn't have helped.

"It doesn't matter. When it's my turn to pitch, you are supposed to go out there and get a job done. And I didn't do that today," Matusz said.

"It's disappointing having an outing like this regardless of the situation. Every time the offense goes out there and puts up eight you want to go out there and shut it down and pitch well. For me I'd like to go out and pitch well every single time. You never want to have an outing like this."

The game featured an exhibition rarity, Pirates catcher Russell Martin argued about pitches with home plate umpire Chad Fairchild so vehemently that he was ejected from the game. Martin missed Dickerson's home run.

Outfielder Trayvon Robinson suffered a strained lower back in the first inning, and left the game.

Steve Pearce had his sixth home run of the spring for the go-ahead run in the seventh. The game took 3 hours, 37 minutes and featured a 16-minute rain delay.

MINOR MATTERS: The Orioles traded minor league outfielder Ronnie Welty to Philadelphia for right-handed pitcher Julio Rodriguez.

"He has all the ingredients you look for in a young pitcher: size, arm, stuff," Dan Duquette, the Orioles executive vice president of baseball operations said.

Rodriguez, who was 7-7 with a 4.23 ERA at Double-A Reading is expected to start at Bowie.

COMING UP: The Orioles host Boston today. T.J. McFarland gets a start. Boston is starting Graham Godfrey. Clayton Mortenson, Jose DeLaTorre and Anthony Carater will follow. The game will be on ESPN. Miguel Gonzalez pitches at Twin Lakes Park against Red Sox minor leaguers.

It's McFarland's first start. The Rule 5 draft pick has pitched eight scoreless innings, allowing just three hits and no walks in his last three appearances.

"I was getting used to coming out of the pen. Now I'm going to start," McFarland said.