OXFORD United have signed Jonathan Mitchell from Derby County on loan until January as cover while Simon Eastwood recovers from a nasty finger injury.

United’s No 1 is recovering from surgery on Saturday night, having suffered a serious dislocation to the little finger on his right hand.

It is thought it could be November before he is available again and given the timeframe, U's head coach Karl Robinson does not think the back-up options are ready to play such an extended block of games.

Mitchell has played five senior games for Derby, the most recent of which was in a 3-2 Carabao Cup defeat to Barnsley 11 months ago.

And it is thought the paperwork was filed in time for him to make his debut in the same competition tomorrow night, when Coventry City visit the Kassam Stadium in the first round.

The 23-year-old has had one loan spell before, playing five matches for Luton Town in 2016, while he has also appeared once for England’s under-21 side.

Mitchell is United's sixth loan - one more than is permitted in an 18-man squad on a matchday, but with on-loan midfielder Samir Carruthers out injured until October it would not be an issue for several weeks.

Robinson said: "It’s a shame because we wanted to use this other loan and we had a player lined up to come in this week.

"We’ve had to say no and use it in another area."

United did have alternative options to Eastwood in the squad.

Scott Shearer, 37, played in Saturday's 2-0 defeat to Fleetwood Town, while there are also Jack Stevens and Manny Agboola at the other end of their careers.

But Robinson said: "We’re going to Portsmouth, the Stadium of Light, some of the biggest grounds in the league.

"Even though I’m an advocate of playing young players, at the same time you can’t ruin them.

"An error in front of so many people can have a detrimental affect on their career.

"It’s when they’re able to cope with the demands of those mistakes in the big games that you know they’re ready to play.

"I’m not willing to risk that just yet.

On Shearer, he added: "He’s here to be the No 2 and support what we’re trying to do.

"He’s got years of experience to pass on. I think the world of him and he brings a lot more. 

"(But to play) two months at his age, he’s had a back problem in pre-season and didn’t train for two weeks.

"He had a back problem last year, I can’t risk that."