Jason Day withdrew from the BMW Championship after eight holes on Sunday with back pain, making him ineligible for the Vardon Trophy.

Day has a history of back issues. The world's No. 1 player barely made it through the opening round of the Dell Match Play, considered withdrawing and then went on to win.

He was 2 over for the round and in the middle of the pack when he withdrew.

Day was leading the Vardon Trophy for the lowest adjusted scoring average going into the BMW Championship. While he was sure to be passed by Dustin Johnson, an incomplete round makes a player ineligible for the award.

His agent says Day was being cautious by withdrawing and hopes to be at the Tour Championship.