British Open champion Henrik Stenson withdrew from The Barclays on Thursday with a knee injury.
Stenson, who fired a disappointing three-over-par 74 with a double-bogey and triple-bogey on his scorecard, explained why he decided to pull out after the first round.
"Regrettably, I need to withdraw this week to allow time for an MRI and see what the next step is," the Swede said.
"My right knee, which required surgery in December, 2015, has flared up again."
This is the second time Stenson left an event early this season. He also withdrew from the U.S. Open before finishing his second round headed toward a missed cut. Stenson cited knee and neck injuries during the June event.
Stenson won the British Open and a silver medal this summer at the Rio Olympics following his first injury, so expect him to bounce back and still contend for the FedEx Cup as the play-offs continue.