Brooks Koepka has withdrawn from The Northern Trust because of injury, a decision that means his 2019-20 PGA Tour season is over.

Koepka was expected to make his seventh start in as many weeks at TPC Boston, and at No. 97 in points he likely needed at least a top-20 finish to have any chance of advancing to the 70-man BMW Championship. Instead, he pulled out on the eve of the opening round, citing knee and hip issues.

Last week Koepka missed the cut at the Wyndham Championship, where he confirmed that he is having issues getting over to his left side. He specifyied that the root cause this time is not his left knee, which was operated upon last year and which Koepka re-injured at the CJ Cup in October.

"This is physical," Koepka said. "I know how to do it, I can do it. I just physically can't do it."

The withdrawal brings to a close a turbulent season for Koepka, who recorded just a pair of top-25 finishes in 13 starts. He was a surprise runner-up in defense of his title last month at TPC Southwind, then played his way into contention at the PGA Championship before struggling to a final-round 74.

Koepka joins Vaughn Taylor (rib) as early-week withdrawals at TPC Boston, reducing this week's field to 123. He's expected to make his next start at the U.S. Open in four weeks, where he'll look to finish first or second for the fourth straight year.