Park Ji-sung may have been underrated by the wider football community, but he certainly wasn’t in the eyes of his former Manchester United teammates and Sir Alex Ferguson.The indefatigable South Korean midfielder - nicknamed ‘Three-Lungs Park’ thanks to his remarkable energy levels - must have been an absolute dream to manage.A major superstar in his home country, Park would always do whatever job Ferguson asked him with minimal fuss. Nobody at Old Trafford has ever had a bad word to say about him.Park joined United in a £4 million deal from PSV Eindhoven in July 2005 and went on to play 205 matches for the Red Devils over the next seven years.He won four Premier League titles, three League Cups, the UEFA Champions League and the FIFA Club World Cup.His high-profile teammates often took the plaudits - including the likes of Cristiano Ronaldo and Wayne Rooney - but Park’s contribution was significant, particularly in big matches.One of his most memorable performances came against AC Milan during the 2009-10 Champions League campaign.Prior to the first leg in the San Siro, Ferguson reportedly told Park: “Your job today is not about touching the ball, it’s not about making passes, your job is Pirlo. That’s all: Pirlo.”Park carried out his manager’s instructions to the letter and his man-marking masterclass on the Italian maestro resulted in United sealing an impressive 3-2 victory.As it worked so well at the San Siro, Park was instructed to carry out the same job on Pirlo in the return leg at Old Trafford.Once again, Park executed the gameplay perfectly. United won the second leg 4-0 and Park had kept Pirlo pocketed for a combined total of 180 minutes.

In his 2014 autobiography, ‘I think therefore I play’, Pirlo criticised Ferguson for utilising Park in the way he did.

"Even Ferguson, the purple-nosed manager who turned Manchester United into a fearsome battleship, couldn’t resist the temptation,” Pirlo wrote. “He’s essentially a man without blemish, but he ruined that purity just for a moment when it came to me. A fleeting shabbiness came over the legend that night.

“On one of the many occasions when our paths crossed during my time at Milan, he unleashed Park Ji-sung to shadow me. The midfielder must have been the first nuclear-powered South Korean in history, in the sense that he rushed about the pitch at the speed of an electron.”

But Man Utd fans, including legendary defender Rio Ferdinand, will always remember Park’s performance against Pirlo with a great deal of fondness.

“I remember we played against Milan in Milan and Pirlo was at the centre of everything that they done," Ferdinand said on BT Sport.

“The manager played Ji-sung Park on him, it was a man-marking job, and I’m sure Pirlo woke up the next morning, looked at the bottom of his bed and expected to see Ji-sung Park there.

“He was that good.

“Whatever the manager set out for him to do, whether it was to defend against somebody, stop someone playing or go in there and make a difference in the opposing team’s box, he’d carry that out.”

Park celebrates his 40th birthday on Thursday and United fans have been wishing their hero, who currently works as an ambassador for the Red Devils, many happy returns…