Mackay is already without defender Lloyd Doyley, while Andreas Weimann and Danny Drinkwater are both looking to shrug off knocks ahead of Saturday's visit of Millwall.

BBC: Watford's Stephen McGinn set for long lay-off

Watford had already seen Lloyd Doyley and Will Buckley limp off, and they suffered a further setback when proceedings were halted while Cleverley received lengthy treatment.

BBC: Sport - Football - Watford 1-1 West Brom

But midfielder McGinn is likely to join defender Lloyd Doyley on the injury list, while captain John Eustace will serve a one-match ban after receiving two yellow cards at Doncaster.

BBC: Watford boss Malky Mackay hopes to boost squad

Full-back Lloyd Doyley caused problems with a surging run into the area before the Hornets player of the season Danny Graham spurned a golden opportunity, heading wide when unmarked at the near post.

BBC: Watford 0-2 QPR

On-loan Manchester United midfielder Tom Cleverley was at the heart of Watford's best chances, sending through Lloyd Doyley midway through the second half, but the defender's cross was scuffed wide by striker Danny Graham.

BBC: Sport - Football - Watford 0-0 Nottm Forest