The Irishman has been feeling his way back into Premiership action following hip surgery, but he picked up a hamstring injury during the 2-1 win at Old Trafford.
Red Devils boss Sir Alex Ferguson wanted to take the combative midfielder off shortly into the second-half, but Keane refused to be substituted with the game delicately poised.
The decision appeared to backfire on Keane, as he pulled up sharply late in the game and was a virtual passenger for the final five minutes.
Following the game, a clearly concerned Ferguson said: "Roy has a sore one. Roy has got a hamstring.
"The intention was to take him off after five minutes of the second-half, but he would not come off. Typical Roy really."
Red Devils hero Mikael Silvestre also picked up a knock and the two will have scans on Thursday.
