Arsenal boss, Arsene Wenger has said he believes there is an underlying reason for Aaron Ramsey's continuing injury woes – but Arsenal have yet to find it.

The Wales midfielder was a substitute for Tuesday night's Premier League defeat of Leicester, but was replaced after only nine minutes due to a hamstring problem.

"We haven't found the underlying reason," Wenger told a news conference ahead of Sunday's FA Cup fifth-round tie at home to Middlesbrough. "There is clearly a reason, whether it is medical or biomechanical.

"He is a guy who is serious. He works hard and has a controlled and disciplined life so there is no reason why he should have muscular problems.

"We have individualised training for the players and [injury] prevention for the players and that is not a case that has been neglected. It is just we have to find the reason why that happens. This is just a small injury, a grade one [hamstring tear]. We are looking at a couple of weeks."