Alex Ferguson accused Ashley Cole of a reckless tackle on Javier Hernandez during Manchester United's 3-1 win over Chelsea at Old Trafford.
Hernandez was forced off due to injury in the second half of United's fifth straight win of the season after being on the wrong end of what Ferguson felt was a "shocking tackle" from the England full back.
It is not known fpr how long the Mexican will be sidelined.
However, Hernandez was in obvious pain as he hobbled down the tunnel and Ferguson was not impressed.
"It was a shocking tackle," he told MUTV.
"The referee booked him, so I don't understand why he hasn't given a penalty.
"Ashley Cole is very reckless at times. He is committed of course but being committed you can sometimes go over the edge a bit.
"That was an example of that."
Even Chelsea boss Andre Villas-Boas admitted it was not the greatest tackle. However, Villas-Boas felt the incident might not have happened if the officials had got two earlier offside decisions correct, which would have wiped out goals for Chris Smalling and man-of-the-match Nani.
"Maybe he wouldn't get sent off if the linesman does his work," said Villas-Boas. "He [Cole] would have been less emotionally drained.
"I work the other way round. You are trying to say the referee did something wrong. I cannot forget the previous two.
"If it was 0-0 maybe Ashley is a little bit more mentally in control of the situation and doesn't do the red card foul that you mention."
Phil Dowd's decision to book Cole means that the matter is now dealt with, although television replays indicated the Chelsea man had been lucky to escape with only that sanction.
