The 25-year-old found the net 34 times in 99 appearances during his two-season loan spell at Old Trafford, but Ferguson baulked at the fee he was asked to pay to make Tevez's move permanent and he was eventually snapped up by City.
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- Man City 2-1 Man Utd
- As it happened
After Ryan Giggs had given United an early lead, Tevez grabbed the equaliser from the penalty spot before heading home the dramatic second-half winner for Roberto Mancini's team.
Ferguson refused to be too downhearted though, saying: "It is just the way these things happen. Football can be like that. It can bite you.
"We have had a few players leave the club and score against us. There is no issue. I am happy with the players we have got.
"We played well and dominated the match. We were reasonably in control, but we had a mad five minutes before half-time that brought them back into the game.
"Everyone can see the penalty for themselves. It is the kind of decision that has gone against us, but could go for us on another day.
"But with the crowd at Old Trafford and the occasion and what is at stake we will be okay."