At a sponsor’s event inside Old Trafford earlier this week, not far from where his statue stands outside the famous stadium, the conversation flows with the Manchester United hero until the subject of his controversial goal in the 1974 Manchester derby is raised.

“I can’t remember it. I just can’t remember it,” Law says, bluntly.

Whether time has erased any memory of the goal or Law is just being evasive, the Scot does not want to talk about it – and it is easy to see why.

United fans labelled Law ’The King of Old Trafford’ after scoring 237 goals, but on April 27, 1974 he was booed off by the home crowd at that famous ground after scoring against his former team for City.

In what was the penultimate game of a nightmare season for United, the then 34-year-old backheeled Francis Lee’s square pass beyond Alex Stepney to hand Manchester City a 1-0 win.

United needed a win to keep their hopes of survival alive. Other results meant they would have gone down anyway – but in the eyes of the home fans, the King had relegated his old club. Law did not celebrate and was immediately substituted.

Law may have tried to forget it, but on Sunday when Louis van Gaal’s United head to the Etihad Stadium, the former striker will be made aware of the goal again by the fans in blue.

“Occasionally City fans try to remind me of it,” Law said with a wry smile.

Law made his name at United as part of a Holy Trinity which included three of the best players ever to grace the Old Trafford turf.

Sir Bobby Charlton and George Best, who both used to describe Law’s play as “electric”, completed the three-pronged attack.

United’s modern-day equivalent comprises Robin van Persie, Radamel Falcao and Wayne Rooney.

Rooney has been missing for the last three games through suspension, so Law is delighted the 29-year-old captain will return for Sunday’s game.

“It’s an incredible boost to have Rooney back,” Law added.

“He and Van Persie are two of the best strikers in the world really. I would love to play with them.”

As far as compliments go, that is probably as good as any Manchester United player will get.

Law has been a fan of Rooney since he signed for United a decade ago.

The Scot has watched the England captain inch closer and closer to his tally of 237 goals for the club.

Rooney is now just 18 short of Law, who is second in the all-time scorers list behind the 249-goal Sir Bobby Charlton.

Law is convinced Rooney will surpass his total this season and then go on to reach Charlton’s landmark.

“I am sure he can (pass my total) it this season,” Law said.

“And stay away from injuries he will be the highest scorer in Manchester United’s history.”

United are confident of victory having watched their opponents across town go three matches without a win.

Van Gaal’s men also snatched a creditable draw against the all-conquering Chelsea last weekend, but Law does not think that necessarily means the visitors will come away with anything on Sunday.

“United played well and got a good result against Chelsea, but the derby game is another game altogether,” he added.

“Derby games could go any way. It’s not always the best team who wins the game.”

That said, Law thinks United are heading in the right direction under Van Gaal, who has won just three of his eight matches in charge.

“I feel momentum is building,” Law said.

“It’s always a bit difficult when a new manager comes in, you have to get to know the players. It’s not easy.

“It’s very rare that you would settle in straight away. Once he gets what he wants as a team and the way it plays you will see the rewards and it will get better and better, guaranteed.”

Law hopes Van Gaal can provide him with a derby result he will want to remember rather than forget on Sunday.

:: Denis Law was speaking at the unveiling of the ’Treble Collection’ and customised First Team squad watches by Bulova, Manchester United’s Official Timekeeping partner.