The Texas Rangers purchased the contract of pitcher Roy Oswalt from Triple-A Round Rock on Friday so the veteran can make his 2012 debut against the Colorado Rockies.

The 34-year-old right-hander signed a minor league contract with Texas on May 29 and went 1-1 with a 5.87 earned run average in four starts between Triple-A Round Rock and Double-A Frisco.

Oswalt pitched to a 9-10 record with a 3.69 ERA in 23 starts last season for the Philadelphia Phillies. He spent time on the disabled list on two occasions -- April 27-May 15 and June 24-August 6 -- for inflammation in his lower back.

Friday will be his first MLB appearance since allowing five runs over six innings in a loss to the St. Louis Cardinals in last year's National League Division Series.

To make room on the roster, Texas placed first baseman Mitch Moreland on the 15-day disabled list, retroactive to Wednesday, with a left hamstring strain and also designated pitcher Mark Hamburger for assignment.