BALTIMORE -- Left-hander Erik Bedard threw a 30-pitch simulated game on Wednesday at Oriole Park at Camden Yards.

"He'll throw one more sim game in Oakland on Monday or Tuesday and probably stretch that out to 40-45 pitches," manager Don Wakamatsu said. "He had no problems."

If all goes well after the next simulated game, Bedard might go out on a rehab assignment, probably in Arizona, to build his pitch count to the 90- to 100-pitch range.

There is a chance that he could make his first regular-season start before the end of this month.

Wilson placed on 15-day disabled list

BALTIMORE -- Persistent discomfort behind his right knee sent shortstop Jack Wilson to the disabled list on Wednesday.

He volunteered.

"I approached them about it," he said. "I don't want to handicap the team anymore, and if it's going to take three or four more games, let's get somebody in here that keeps [manager Don Wakamatsu] from getting his hands tied."

The Mariners replaced Wilson on the 25-man roster with Matt Tuiasosopo, recalled from Triple-A Tacoma.

"It was one of those things where I have already served a week, or whatever it is, so let's let this go away," Wilson said. "Could I possibly play in three or four days? Maybe. But at the same time, I don't want to hurt the team more by going out on the field when I'm not ready."

Wilson has tendinitis behind his right knee and has been out of the lineup since May 5.

He plans to take it easy for a few more days and then go out on a rehab assignment before returning to the Mariners' lineup.

"I want to be out there, but I don't want to be out there and hurt the team," Wilson added.

Tuiasosopo had just arrived in his Nashville, Tenn., hotel room when he received a call from Tacoma manager Darren Brown to get back on a plane and come to Baltimore.

"I was able to go down and play every day," Tuiasosopo said. "I got eight games in, played left field, played first base and it went well. The last couple of days have been kind of crazy, but I hope to come here and continue to play well."

Bradley making progress

BALTIMORE -- Left fielder Milton Bradley could rejoin the team at some point during the Mariners' next homestand, manager Don Wakamatsu said on Wednesday.

Bradley has been on the restricted list since May 5 with stress-related issues.

"I think everything is going well," Wakamatsu said. "Tentatively, we're hoping that at some point in the [next] homestand, he'll be able to rejoin the team."

Bradley, acquired from the Cubs for pitcher Carlos Silva during the offseason, was batting .214 with two home runs and 12 RBIs this season.

The fluid DH position

BALTIMORE -- Jose Lopez was in the designated-hitter spot for the first time this season.

"We talked about putting guys who are playing well in there, and the best possible lineup out there," manager Don Wakamatsu said. "[Ryan] Langerhans, Josh Wilson and [Michael] Saunders are all playing well, and if you look historically with Lopez's start last year, it was about the same."

Lopez went into Wednesday night's game against the Orioles with a .214 batting average, one home run and 12 RBIs.

But he has played superb defense at third base, and may be focusing so much on that aspect of his game that his offense has suffered.

He was batting .248 with three home runs and 19 RBIs on May 12 last season.

"We chose to give him a DH day instead of an off-day," Wakamatsu said.

Mike Sweeney will be the designated hitter in Thursday afternoon's series finale against the Orioles.

Worth noting

Center fielder Franklin Gutierrez was not in the starting lineup for the first time this season, sitting out Wednesday night's game with stiffness in his lower back. He is listed as day-to-day. ... Left-hander Cliff Lee, who won his first game of the season on Tuesday night, is the first Mariners pitcher to begin his Seattle career with three consecutive walk-free games. Lee is one of just four Mariners pitchers to have back-to-back-to-back starts with no walks. The others are Jamie Moyer (2002), Freddy Garcia ('01) and Aaron Sele ('01). ... No. 4 and 5 starters Doug Fister and Jason Vargas are 5-3 with a 2.44 ERA.