Defender to have four weeks' worth of rest to cure knee pain.

Defender Mark O’Brien is to miss the next four weeks of Derby County’s season.

The 20-year-old centre-back, who has made 11 appearances for Derby this season, recently made his comeback from a long-term cruciate ligament injury which was sustained halfway through last season.

However, O’Brien has been playing through the pain barrier in recent weeks after sustaining damage to the surface of his knee joint, which requires rest in order to clear up.

Clough has confirmed O’Brien will now take his enforced break and has eased fears that the Republic of Ireland Under 21 international requires anything more than rest: “Mark needs four weeks of rest as his knee has not settled down in the last week or so, so that’s started as of now.

“It got to the point where Mark couldn’t play at Sheffield Wednesday last weekend because of the pain, so he needs to take a break now.

“It’s nothing to be worried about; we just have to remember that he was out of action for 13 months and returning into competitive action with games coming thick and fast can take its toll on his knee.”

Clough has also revealed his excitement, already, of O’Brien taking part in a pre-season for the first time since signing professional forms in 2010.

Injury problems have hit the Dublin-born Academy graduate in recent years and Clough believes the best of him is still to come.

“We’re looking forward to him actually having a pre-season with us because in all the time he’s been here, I don’t think he’s had one,” he said.

“We’ll look after him for the next few months, get him through the rest of the season and then we’ll get him in for pre-season.

“That’ll hopefully be a catalyst for him to build on his excellent form in the last few weeks because he’s certainly proved his worth when he has been in the side.”