Just days after winning the sport's top prize, the FedEx Cup, Irishman Rory found himself playing with the pop star ahead of the Omega European Masters tournament on Wednesday (August 28).
And when Justin struggled to get himself out of a sand trap near a green, the professional stepped in to give him a few tips.
In video from the moment posted online, Justin listens carefully as McIlroy shows him what he's doing wrong.
To make the little lesson extra special, after Timberlake lifts the ball out of the sand and onto the green, it rolls towards the hole, hits the flag and comes to a stop a yard away.
Timberlake is not exactly a novice - the "Cry Me a River" hitmaker has a 2 handicap and has garnered a reputation as one of the best celebrity golfers on the planet - up there with Alice Cooper, Samuel L. Jackson, and Dennis Quaid.
Meanwhile, Rory has a few celebrity friends - fellow Irishman Niall Horan, who often shows up at tournaments to cheer him on, has served as the pro's bag-carrying caddy.