New York Yankees pitcher Randy Johnson will miss his scheduled start on Thursday because of back pain. The 41-year-old lefthander had an MRI on Monday that showed inflammation of the lumbar spine. Although the injury is not considered serious and Johnson insisted he would be ready to pitch, Yankees manager Joe Torre will hold him out of Thursday's meeting with Texas. Torre told the New York Times that he'd rather err on the side of caution than risk further injury to his pitcher. He also added that Scott Proctor will likely take Johnson's turn in the rotation. Johnson took the loss in an 8-5 setback this past Saturday in Toronto and apparently began experiencing the back pain during the contest. He lasted only four innings and was charged with six runs -- five earned -- on 10 hits with a walk and three strikeouts. The next day, he arrived at Rogers Centre in Toronto with back stiffness and spasms. The veteran hurler was supposed to be the Yankees' ace this year, but has had a mediocre season so far, posting an 11-7 record with a 4.29 ERA in 24 starts. New York's rotation is already thin with Kevin Brown, Carl Pavano, Jaret Wright and Chien-Ming Wang on the disabled list.