But the Blues title-winning captain was in the midst of a gambling hell when he delivered a legendary display in a 5-0 win at Millwall, as his team stormed to the Premier League.
And that led to Pompey boss Harry Redknapp stuffing £30,000 in cash down his trousers during the game at The Den, for Merson to settle a debt.
Redknapp’s men went to south east London with their title charge at full throttle in March 2003, and then executed a demolition job on the Lions.
It was Merson who was at the heart of the victory, as he pulled the strings with a display which has gone down in folklore.
Despite enjoying a career which delivered silverware with Arsenal and saw the midfielder turn out for his country along with spells at Aston Villa and Middlesbrough, it’s that performance which is the high watermark of Merson’s time in the game.
He told The Guardian in an interview to publicise his new book, Hooked: ‘People ask: ‘What was it like when you won so much at Arsenal and played for England? I don’t know.
‘All I remember was winning the league at Portsmouth. I wasn’t drinking, I wasn’t gambling too much and I sucked it in.
‘I remember one game we played (against Millwall).
‘Portsmouth and Millwall don’t like each other and so none of our fans were allowed in. I also remember having 30 grand, in cash, to give to someone after the game.
‘Harry said: “What is it, Merse? A watch?” I said: “No, I’ve got some money.” Harry shoved 30 grand down his big, baggy tracksuit bottoms.
‘I went out and had the best game of my career. We were 5-0 up and I got a standing ovation from Millwall fans with five minutes to go.
‘Then, in the car park, this 75-year-old geezer comes up to me: “I just want to say, Merson, I’ve been coming to The Den 60-odd years and I’ve never seen what I seen today. We’ve never had a standing ovation for an opposition player”.’’
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