Derby's 16-year-old defender Mark O'Brien has undergone heart surgery. The Republic of Ireland Under-16 international had surgery on heart valves at Leicester's Glenfield Hospital and now faces a three-month rest before resuming his promising career.

The problem was first spotted in pre-season and medical staff began to monitor his condition but after consulting a number of experts it was decided he should have the operation.

"I was taking things in my stride to be honest and once he (the consultant) said 'it is next week' I did get a little nervous," O'Brien, who made his first-team debut last season, told the club's official website.

"I'm feeling quite stiff, but apart from that I'm feeling great to be honest. Everything is going according to plan which is good.

"I'm glad it (the operation) is out the way now because I didn't want to wait until next year which was initially spoken about.

"I didn't want to have it in the back of my mind for the next five or six months."