Roy Keane labelled Kyle Walker "an idiot" after the Manchester City defender conceded a penalty in his side's 1-1 draw with Liverpool.
Walker brought down Sadio Mane in the 13th minute of the Premier League contest at the Etihad Stadium, with Mohamed Salah converting the resulting spot-kick.
City's players felt Raheem Sterling had been fouled in the lead-up to the incident but their protests were waved away by referee Craig Pawson.
Analysing the game for Sky Sports, former Manchester United captain Keane said: "I think it is an initial foul but I think the referee, to be fair to him, is looking at Sterling and thinking he's in the penalty box, he's taken another touch on the ball and trying to play the advantage."
Asked by presenter David Jones how Mane earned himself a penalty seconds later, Keane added: "Because he's up against an idiot.
"Kyle Walker, people tell me he's playing well – I don't think so. I think this guy is 30 years of age, international player... he's a car crash, keeps making these types of mistakes and rightly punished for it."
After the match, Keane said: "He's got that daftness and can make idiotic decisions. When he compounded his first mistake with the second I wasn't surprised.
"Some of his defending over the years is shocking. Still doing the same daft things...he'll never learn.
"When he dangled that leg in he knows Mane's going to go down – and he's got a team-mate inside him. He doesn't have to do it."
Fellow pundit and former Liverpool defender Jamie Carragher added: "I don't think he's ever going to change, at his age.
"He's a defender who makes mistakes and poor decisions when he's not concentrating – but the other things he gives you outweigh that."
Former City defender Micah Richards, who is now a pundit, said: "I just feel like we're being a little bit harsh on him because he's been outstanding this season.
"He (Walker) doesn't make big mistakes...it's just unfortunate when he makes a mistake it's going to be highlighted."
