I felt a little twinge this morning, but I stretched it out and it was feeling OK, Toms said. I hit my drive and about went down to my knees.
Toms, who had been playing his best golf in a season and a half, will have three weeks to be on the mend in time for the U.S. Open in June. He was not planning to play in either next week's Memorial or the Kemper the following week.
Toms said he will go home to see his doctor after realizing he would be unable to finish his round on Thursday.
He came in to the Colonial with high expectations after his superb victory at the inaugural Wachovia Championship two weeks ago and an impressive sixth place finish last week at the Byron Nelson Classic.