Rory McIlroy is merely one of Manchester United's avid supporters, with the English Premier League club being one of the most-supported football teams in the world (their Facebook page, for instance, boasts more than 70 million followers).
The former world No. 1 golfer and four-time Major winner is not the only high-profile sports star who counts himself as a Red Devils fan.
The Straits Times looks at others.
1. Usain Bolt (athletics), Jamaica
It is perhaps no longer a secret that the Jamaican sprinter is a big fan of United. The 31-year-old had openly expressed his desire to play for the club back in 2012 during the Olympics in London.
Now that he has hung up his spikes, Bolt has more time to attend United matches and was recently seen at Old Trafford during the 2-0 win over Leicester in August 2017.
Speaking to the club's official website (www.manutd.com) in September, he said that he was initially attracted to United by their former Dutch striker Ruud van Nistelrooy, who scored 150 goals in 219 appearances for Alex Ferguson's team.
2. Floyd Mayweather (boxing), United States
The undefeated boxing champion (50-0) is a surprise name, simply because he is not too familiar with football himself.
During an earlier interview in 2017 with former United defender Rio Ferdinand, Mayweather was asked to pick between United or their city rivals Manchester City.
"Who has the better record?" he asked, before Ferdinand replied, "Manchester United."
Mayweather then said, "Well that's who we're rocking with, baby!"
The 40-year-old once famously wore a United shirt to antagonise die-hard City fan and opponent Ricky Hatton. There is little doubt where Mayweather's allegiance lies.
3. Greg Rutherford (athletics), Britain
The long-jump Olympic gold medallist previously admitted that he had always supported United since he was a kid, because his dad was a big United fan.
During an interview with The Sun newspaper, the 30-year-old named Paul Scholes as his favourite United player and said that Ryan Giggs' goal against Arsenal in the FA Cup semi-final replay in 1999 was his greatest United moment.
Rutherford added that he had always been a decent footballer and even had trials at Aston Villa before taking up athletics on a full-time basis.
4. Tomas Berdych (tennis), Czech Republic
The 32-year-old once revealed to the Daily Mail that he is a "big fan of Manchester United" and that he will always cherish the experience of watching his favourite team play in the Champions League final against Barcelona in 2011, even though they were defeated 2-0.
The Czech also had a chance to meet United stars Juan Mata, Ander Herrera and Antonio Valencia in Washington in 2014, together with fellow tennis player Jamie Murray - who is also a United fan.
