If Rory McIlroy is to add a fourth FedEx Cup title to his resume, he'll have to do so battling a back injury.

As reported by Golf Channel's Todd Lewis, McIlroy suffered an injury to his lower back earlier this week at his home in Jupiter, Florida.

Despite dealing with what Lewis says is a “muscular issue,” the Northern Irishman still made his way to Atlanta's East Lake Golf Club after taking a few days off following his fourth-place finish at the BMW Championship at Olympia Fields this past Sunday.

McIlroy, who enters the Tour Championship in third place in the FedEx Cup standings and started his week at 7-under in the staggered-stroke season finale, hadn't hit a golf ball all week until he began his practice session on Thursday morning.

The world's second-ranked player, of course, is looking for his second consecutive Tour Championship victory and his fourth overall win at East Lake.

A year ago, McIlroy overcame a six-shot deficit during Sunday's final round en route to a final-round 66, ending his week at 21-under to best Scottie Scheffler and Sungjae Im by a single stroke. The victory marked Rory's third FedEx Cup championship, giving him the most in history. The current world No. 2 also took the title in 2016 and 2019.

Tiger Woods is the only other player in PGA Tour history to win it more than once.

With an $18 million first-place check and a $75 million total prize pool up for grabs, Rory McIlroy kicked off what will likely be a painful week in the penultimate group of Thursday's first round, playing alongside world No. 3 Jon Rahm.