Watford have major selection worries ahead of the home clash with fellow strugglers Plymouth.
On-loan Manchester United youngster Tom Cleverley was on Thursday ruled out for the rest of the season with the knee ligament damage he suffered in Monday's 1-1 draw with West Brom.
Jon Harley is suspended following his red card against the Baggies and fellow midfielder Henri Lansbury completes his two-match ban.
Full-back Lloyd Doyley and winger Will Buckley have picked up hamstring injuries and will be assessed closer to kick-off while centre-half Martin Taylor and striker Heidar Helguson are struggling to shake off the knocks which kept them out on Monday.
Jay DeMerit, Ross Jenkins, Stephen McGinn and Ryan Noble are pushing to be involved.
Plymouth could be boosted by the return of skipper Carl Fletcher ahead of the vital clash.
Fletcher has missed Argyle's last three games after suffering a knee injury in the 2-0 home defeat by Blackpool in March, but is contention after returning to fitness.
Winger Craig Noone has missed the last two games with a knee injury and he may be available, depending on how he reacts to a cortisone injection he had in the week.
Central defenders Kari Arnason (hip) and Krisztian Timar (hamstring) are sidelined by injury along with full-back David McNamee (hamstring).
With four games remaining and ahead of their crunch trip to Vicarage Road, Argyle are 23rd in the table, four points behind safety and 21st place Watford.
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