Hector Bellerin could be set to miss Watford’s clash with Arsenal after Arsene Wenger confirmed the defender has suffered a knee injury.

The Spanish right-back is a certainty to be unavailable for the Gunners’ Europa League meeting with AC Milan tonight and joins Nacho Monreal and Alexandre Lacazette in the treatment room.

Under-fire Arsenal boss confirmed the flying full-back has been sent to see a doctor to get to the route of the problem.

He said: “He has injured his left knee. He had a scan which showed inflammation, it needs further investigation to why he is in pain.

“He could not absorb the training session, so we had to leave him behind.”

Watford will look to inflict further woe on Wenger and Arsenal on Sunday as they attempt to extend their own winning run to three straight games.

Doing so would all but seal their top flight status for another year and leave Arsenal in further disarray.

The Emirates Stadium club have lost their last four games on the spin and most are expecting them to struggle at the San Siro this evening.