Rory McIlroy was upstaged by a heckler in the gallery at the Ryder Cup Thursday morning -- when the golfer missed a putt multiple times ... and an American heckler came out and showed him how it's done!
Rory was doing a practice round at Hazeltine National Golf Club in Minnesota when he got to the 6th hole and ran into some trouble on the green.
The heckler essentially told Rory he could do it better ... so Henrik Stenson challenged the guy to come out on the course and hit it himself.
Golfer Justin Rose even put up $100 to the heckler if he made the shot.
Well, guess what -- HE DRAINED THE 12 FOOT PUTT ... while wearing jeans and what appeared to be house slippers!!!
Rory wasn't bitter -- in fact, he gave the guy a hug and helped him celebrate.