ROB Hall will seek medical advice today as Oxford United look to get to the bottom of his knee injury.

The winger reported back for pre-season with an issue and despite building up his game time slowly, problems remain.

After being rested for the Carabao Cup tie with Coventry City, he was due to start against Portsmouth.

But the 24-year-old’s knee swelled up after training on Friday and he was withdrawn.

It is a concern for Hall, who ruptured knee ligaments in 2016 and then missed five months last season with cartilage damage.

U’s head coach Karl Robinson said: “Rob Hall is seeing a specialist on Monday to find out how bad that knee really is, which is not great.”

Ricky Holmes also missed the 4-1 defeat at Fratton Park after getting an injection on a long-standing back issue.

The Sheffield United loanee is likely to miss tomorrow night’s home game with Accrington Stanley, but could return in time for Burton Albion’s visit this Saturday.

The pair join Simon Eastwood and Samir Carruthers, ruled out until the autumn, in a busy treatment room.

Robinson said: “They’re all knocks.

“If it was hamstrings and thighs over and over again we’d start questioning what we were doing.

“But when you’re getting knocks in games it’s hard to contend with.”