CARMEL, Ind. — 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, most recently at the Dell Match Play in the spring. The world’s No. 1 player barely made it through the opening round when his back locked up on him and he considered pulling out. The back got better, and Day went on to win.

He was 2-over par for his final round at Crooked Stick and in the middle of the pack when his agent, Bud Martin, said he felt pain stooping to pick up his tee.

The injury was not considered serious, and Day was hopeful of being in Atlanta in two weeks for the Tour Championship and a shot at the $10 million FedEx Cup bonus.

The Australian was leading the Vardon Trophy for the lowest adjusted scoring average going into the BMW Championship. He was ahead by a slight margin over Dustin Johnson, and Johnson was sure to pass him easily going into the final event.

However, players who withdraw in the middle of a round are not eligible for the award from the PGA of America, which dates to 1937.

Day went straight for treatment.

“I don’t think it’s anything he hasn’t dealt with before,” Martin said. “He just bent over and it kind of went on him on the ninth hole. Instead of forcing it, we just decided that it was more prudent to come in, get it worked on and deal with it.”

Martin said Day might choose to have more tests next week just to be sure, but “my gut is that he’ll be fine.”

The PGA Tour is off next week. The Tour Championship for the top 30 players starts Sept. 22 at East Lake.

“Hopefully, he’ll be ready for Atlanta,” Martin said. “But the most important thing is the next 15 years, not the next 15 days.”