Tiger Woods withdrew from The Northern Trust hours in advance of his scheduled second-round tee-time on Friday.
Woods, playing in just his fifth event since winning The Masters in April, laboured to a first-round 75 to sit towards the bottom of a 121-man field at a course where he'd twice been runner-up previously.
Shortly after 11am local time on Friday, he confirmed that he would not be joining Scott Piercy and J.T. Poston on the tee for round two.
"Due to a mild oblique strain that led to pain and stiffness, I have to withdraw from The Northern Trust," Woods said in a statement.
"I went for treatment early Friday morning, but unfortunately I'm still unable to compete. I'd like to thank the New Jersey and New York for their support and remain hopeful I can compete next week at the BMW Championship."
As reported by Golf Channel's Will Gray, it is the first time Woods has withdrawn from an event during play since the 2017 Dubai Desert Classic, after which he underwent spinal fusion surgery and spent 10 months on the sidelines.
Woods leads the US Presidents Cup side in Australia next month and will need to select himself as a wild-card if he's to take up a role as playing captain.
Before that, his place at the TOUR Championship - the final event of the season on the PGA Tour and one he won last year to cap a fine comeback campaign - is under serious threat.
Woods started The Northern Trust ranked 28th in FedEx Cup points and, with this week's event and the BMW Championship to come, is set to fall outside of the top 30 and therefore fail to quality if he does not tee off at Medinah on Thursday.