The Orioles' four-man rotation to start the season is set after Brian Matusz threw a bullpen session Wednesday and pronounced himself ready to go and the team announced that Chris Tillman will start Sunday in Game 3 against the Tampa Bay Rays.

Tillman beat out Brad Bergesen with Justin Duchscherer starting the season on the disabled list and top pitching prospect Zach Britton beginning at Triple-A Norfolk.

Jeremy Guthrie will start Opening Day on Friday at Tropicana Field. Matusz and Tillman will follow him, and Jake Arrieta will start Monday's home opener against the Detroit Tigers at Camden Yards. Bergesen, meanwhile, will go to the bullpen and likely be the top candidate to join the rotation April 10, when the Orioles need a fifth starter.

Neither Tillman nor Bergesen had a particularly good spring. Tillman, a 22-year-old right-hander who made the Opening Day roster for the first time, had a 3.93 ERA in five spring outings, but he allowed 20 hits, nine walks and hit two batters in 181/3 innings. Bergesen, 25, pitched to a 5.82 ERA over six spring starts, surrendering 25 hits and six walks over 17 innings.

In his final start Friday, Bergesen was drilled in the right forearm by a liner off the bat of the Minnesota Twins' Denard Span. He threw two innings Wednesday against Orioles minor leaguers and had no issues.

The battle for the final rotation spot essentially became a two-man competition after Duchscherer was sidelined and other options, such as Ryan Drese and Rick VandenHurk, struggled. Britton was the Orioles' most effective starter all spring, but the club didn't want to sacrifice a year of his service time just to have him in the rotation for the first 21/2 weeks.

Britton is on schedule to rejoin the club and make his big league debut later in April. Barring any setbacks with his surgically repaired left hip, Duchscherer is in line to come off the DL and start April 21.

If he struggles, that would mean a short stay in the rotation for Tillman, who has a 5.61 ERA over 23 big league starts spanning the past two seasons.