Michael Owen has revealed that being forced to watch games from the bench is turning him into a nervous wreck.
The England international has struggled to hold down regular first-team football since joining Manchester United as a free agent this summer.
He is yet to really make his mark at Old Trafford, although he went a long way to doing so with his derby exploits on Sunday.
Owen was a late substitute against Manchester City, but his goal scoring instincts saw him in the right place at the right time as he snatched the decisive seventh goal in a thrilling 4-3 victory for Sir Alex Ferguson's side.
He admits the sense of occasion almost got to him as he was awaiting his opportunity, but was delighted to have made a decisive impact upon entering the fold with 12 minutes remaining.
"It was brilliant," he said.
"I don't know how the manager and staff do it. It must be so nerve-wracking.
"When I start a game I never get nervous. I always feel in control.
"But when you are sat on the bench the game rubs off on you.
"When you do go onto the pitch you are a little bit nervous because you have felt all the emotions of everyone sat around you. You kick every ball with the team.
"The first couple of minutes are quite hard. It is not like just going down to the park for a kick-around.
"At this level you have to be right into the game, at the right speed despite sitting on your backside for the previous hour, or however long it is.
"But you get sent on to get a goal. Thankfully that is what I did."
Despite putting the first dent in City's 2009/10 campaign on Sunday, Owen still believes that Mark Hughes' side are capable of challenging for a top-four finish this season.
"Manchester City have been quite impressive since the start of the season," said the former Liverpool striker.
"You would think they will be up at the right end of the table.
"Everyone is guessing how far up the table that is. Whether it is a European place or a Champions League place I am not sure. But I definitely think they will be up there."