Robert MacIntyre cited lower back pain in withdrawing midway through the third round of the BMW Championship on Saturday in Castle Rock, Colorado.
The PGA Tour rookie from Scotland had bogeyed two holes on the front nine and was 1-over par for the tournament when he withdrew.
McIntyre, 28, entered the penultimate event in the FedEx Cup playoffs in 12th place in the season-long points standings and is a lock, the PGA Tour noted in a news release on Saturday, to remain in the top 30 and qualify for the Tour Championship next week at East Lake Golf Club in Atlanta.
That's if MacIntyre is healthy enough to play.
He carded rounds of 72-71 to open the 50-player tournament at Castle Pines Golf Club.
He's 15th in the Official World Golf Ranking, and he won this year at the RBC Canadian Open and Genesis Scottish Open.
Hideki Matsuyama of Japan withdrew from the BMW Championship prior to the start of the second round on Friday due to a lower back injury.