The two pals teamed up for the Masters Par 3 contest ahead of the 2015 Masters Tournament at Augusta National golf club.

The 21-year-old singer, who is an avid golfer, donned an all-white one-piece caddy outfit with the professional's name on his back and carried MCllroy's bag around the course, while offering him tips on shots and swings.

Horan's special day at one of the world's most famous golf courses was made complete when he got the chance to meet Tiger Woods, who is returning to the sport after injury.

MCIlroy and Horan have much in common - One Direction released their debut album in 2011, the same year the golf ace won his first major.

Speaking about the unlikely Augusta course partnership before the Par 3 contest, MCIlroy said, "We met in Australia at the end of last year and he was saying he had never been to The Masters. I said if you're available on the Wednesday you're more than welcome to carry the bag. Niall's really excited."