Watford will be without midfielder Tom Dele-Bashiru for the rest of the season because of an ankle injury.
The 23-year-old has not played since damaging ankle ligaments in the 4-0 defeat at Swansea on December 30.
At the time, he was expected to be out for “a couple of months” but has picked up another ankle problem in training.
Watford have also said midfielder Edo Kayembe will be out for “the same period” with a calf strain that means he could miss the rest of the campaign.
Kayembe, 24, has been out of action since 12 November, having played 22 games this season to that point.
Dele-Bashiru, who spent last season on loan with Reading, has made only six appearances this term.
Before the Hornets’ home game with Preston on Saturday, head coach Slaven Bilic did provide more optimistic news on full-backs Jeremy Ngakia and Joao Ferreira.
Former West Ham youth player Ngakia, 22, last played in the 2-0 win over Blackpool in mid-January and has been suffering with hamstring issues, with Ferreira out for the past five weeks.
Both returned to training this week with Bilic set to make a late call on whether to put them in the squad for the weekend.
“They are back, maybe not for this game, but it’s very good to have them back at this stage of the season,” he told BBC Three Counties Radio.
Watford, four points outside the top six, take on Preston, eight points off the play-off places, at Vicarage Road, looking for what would be only a second win in eight Championship matches.