Watford defender Miguel Britos remains a doubt for Tuesday's Premier League clash with Manchester United and he will need another training session to prove his fitness, manager Marco Silva said.

The 32-year-old Uruguayan limped off shortly after halftime during Watford's 3-0 win at St James' Park on Saturday after failing to shake off the knock he picked up following a heavy challenge from Newcastle United midfielder Jonjo Shelvey.

"The situation with Britos we will keep open," Silva told a news conference.

"He is still in doubt. We'll see. I'm not sure if he's able to play. We have one more session tomorrow, one more session to prepare for the match and then we will take the decision."

Sebastian Prodl replaced Britos in the heart of the defence on the weekend and could do so again to make his first start for the club since late August after recovering from a hamstring injury.

"He's improving his physical condition," Silva added. "It's been two months without competition, two months without training with the team. It's hard. He's improving and played almost 45 minutes (against Newcastle). That's good for him."

Watford, currently eighth in the league, will also be boosted by the return of captain Troy Deeney, who is available for selection after serving his three-match suspension.