Rio Ferdinand has accused Carlos Tevez of taking it easy in training during his time at Old Trafford.
Tevez left the Red Devils to join bitter rivals Manchester City in the summer, and is set to meet his former club in Saturday's derby clash at Eastlands.
The Argentina international has scored 22 Premier League goals for Roberto Mancini's side, but England defender Ferdinand has mischievously suggested that the energy Tevez shows on a matchday is not necessarily reflected in his attitude to training.
Ferdinand was quoted in The Sun as saying: "Carlos is an interesting character. When he was at United, he saved all his energy for the games - he didn't really go over the top at training.
"He worked hard in the gym - he was a professional in that sense - but everything he did was geared towards the match at the weekend.
"You could see him conserving his energy during the week and then laying it all on the line out on the pitch.
"That's not the way I operate, I have to train at a high level every day. But it works for Carlos and he can be a real handful to defend against."