Watford manager Walter Mazzarri has hinted that midfielder Roberto Pereyra could be set for a prolonged spell on the sidelines after picking up a knee injury.

Pereyra was forced off in the first half of his side's 2-0 loss at the hands of Manchester City on Wednesday night, being replaced by Camilo Zuniga on the half-hour mark.

Mazzarri revealed that he is still unsure as to the full extent of the problem, but does not expect the 25-year-old Argentine back anytime soon.

"We still have to wait for some evaluations of the MRI and scans. Then we will be able to give an answer, probably after the next game," he told reporters.

"For sure it won't be too short. From my experience I have a feeling that it's not a terrible, terrible injury, but at the same time I think it's not [a] very short [absence] as an injury."

Pereyra has scored two goals in 13 Premier League appearances for the Hornets this season.