Roy Keane revealed the exact moment he knew his career was over.

Portugal’s European Championship hopes ended on Friday evening, with Roberto Martinez’s side falling to a 5-3 quarter-final defeat against France.

It was a game that perhaps marked Cristiano Ronaldo last major championship appearance for Portugal, with the 39-year-old five-time Ballon d’Or having failed to score across the entire tournament.

While insisting the misfiring Ronaldo should at least temporarily step back from international football, Keane recalled the moment he knew it was time to hang up his boots.

Speaking on the Overlap, courtesy of Sky Bet, the former Manchester United skipper said: “For me it was the training – I was at Celtic, and players can try and help you and I was injured, but it was the training and taking painkillers.

“Everything in training was an effort and you’re like, ‘This is just training.’ When you start losing your love of training [you’re like time is up] – we all love training.”

Keane added: “[Cristiano Ronaldo] should have a break and step back from international football, and if he’s still playing at club level, then have a look at the world cup when it comes around.”

Meanwhile, Ian Wright compared Ronaldo’s performances for Portugal to his time at Burnley at the end of his career.

Wright said: “There are certain players that I know that when I was doing my stuff, they wouldn’t have been able to get near me with the movement.

Keane insisted he knew it was time to hang up his boots while training at Celtic (Getty)

“I could not get away from anyone and this is what I’m seeing when I’m watching [Cristiano] Ronaldo, is that he’s doing the stuff, but they [defenders] are there.

“I was 36 and at Burnley – we got promoted at the very end but when you’re playing against certain players and you do stuff – I said to myself, ‘I’m done’.

“Going to Burnley for my first coach at [Crystal] Palace, Stan Ternent, he said, ‘Listen, come, we have half a chance, you’re experienced’, but then when you’re playing you feel, ‘This is embarrassing – I can’t do anything – I can’t even hold some of the ball in games’.”