Sir Alex Ferguson has revealed he still agonises over a decision forced upon him ahead of the 2008 Champions League Final.
Fair to say the Manchester United legend can't have too many regrets from his trophy-laden 27-year spell in charge of the Premier League giants.
But one dilemma as he led United to another Euro glory night after beating Premier League rivals Chelsea on penalties in Moscow still niggles.
It was the second Champions League success for the Glaswegian who was in charge for the club's incredible victory over Bayern Munich in 1999.
But Sir Alex still has a regret over one major decision ahead of the 2008 showdown with the Blues.
The match took place when teams were only allowed to name seven substitutes in Europe's premier club competition, compared to the 12 permitted on the bench now.
South Korea international Ji-sung Park was the unlucky player to miss out.
And in an interview with MUTV, Ferguson said: "To win the European Cup is fantastic. It was a really great bunch of players with a great attitude about them and a good, strong squad.
"My problem in the 2008 final, maybe I even regret it to this day, was I left Ji-sung Park out completely in the final.
"He'd played such a great role and that's the problem when you get to these finals.
"At Wembley [in 2011] I did it to Dimitar Berbatov and he took it badly. He didn't deserve it. No player deserves to be left out of the final.
"That's why we try hard at these European seminars with the coaches to try to get 11 subs in the final.
"You've got four or five sitting in the stand who made fantastic contributions in getting there."
Park did go on to feature for United in both the 2009 and 2011 Champions League finals, but the Premier League giants lost on both occasions to Barcelona.
