But McCarthy put an end to any fears when he headed home the winning goal with just two minutes of the game remaining.
McCarthy said: "I was crapping myself at the thought of penalties after missing one against Bolton.
"When the goalkeeper is having a night like that, you feel he will claw away some of your spot-kicks.
"He was absolutely fantastic. If it wasn't for him, Sunderland would have lost in the 90 minutes.
"My nerves were beginning to play up but then we got the winner. It was a good free-kick by Carlos and a fantastic looping header by me."