BOSTON -- Boston Red Sox pitcher Daisuke Matsuzaka is going to be placed on the 15-day disabled list Wednesday because of a sprain in his right elbow, manager Terry Francona said after Tuesday night's game against the Baltimore Orioles was postponed because of rain.

The right-hander had an MRI done Tuesday afternoon, and the images showed the sprain, Francona said. A more detailed statement from medical director Thomas Gill is expected Wednesday, according to the Sox.

Michael Bowden, who had joined the Red Sox on Tuesday from Triple-A Pawtucket and was in the clubhouse, will be officially called up Wednesday to take Matsuzaka's spot on the roster.

So over the last two days Boston has lost two-fifths of its starting rotation. On Monday, John Lackey (2-5, 8.01) was placed on the DL, also because of right elbow woes.

The Red Sox are looking into their bullpen to replace Lackey and Matsuzaka for now. Tim Wakefield, who was going to start Tuesday night in Lackey's spot, instead will pitch Sunday night's game against the Chicago Cubs at Fenway Park. Alfredo Aceves, who worked three innings of relief in Matsuzaka's start Monday night, will start against the Cubs on Saturday night.

There is no makeup date for Tuesday's rainout.

For more on Matsuzaka and the Sox rotation, click here.