Hornets goalkeeper Manuel Almunia will not feature in this Saturday's match against Blackpool after the Spanish stopper suffered a setback in his recovery from a hamstring injury.
The 35-year-old stopper has missed Watford's last two games against Sheffield Wednesday and Wolverhampton Wanderers but the club hoped he would return this week.
Zola said: “Manuel is not going to be available on Saturday, he has unfortunately had a setback.
"It’s not too bad but he's not going to be able to be part of the team on Saturday.”
When asked how long he thought Almunia would be ruled out for Zola said: “We don’t know that yet.”
Zola also revealed that Fitz Hall will be not available as he is yet to recover from a hamstring strain.
"Fitz hasn't made it yet," he said. "It's taking a little bit longer this time than we thought."
John Eustace, Connor Smith, Prince Buaben and Tommie Hoban are also ruled out but Geoffrey Mujangi Bia trained this week following injury.
New signing Matthew Briggs was not selected for Tuesday night's win over Sheffield Wednesday but Zola said the Fulham loanee will be included in the squad against Blackpool.
"He was fit but he’d just arrived and I thought it was better to give him one game to see how we are and get used to things," said the Watford head coach. "Matthew is definitely involved in the squad for Saturday."
Saturday's clash will be Watford's third game in eight days and Zola is likely to make a few changes.
"Will we make changes? I don't know, we have to consider a few things," he said.
"We are obviously coming towards the end of the season and the games are piling up one after another.
"I will look at where we are tomorrow (Friday) because we have a few players obviously who have a few knocks and we will decide what to do."
After a strong start to the season Blackpool have slipped to 17th in the Championship and have not won in their last five matches but Zola insists it will still be a difficult game.
"They are not in the same position as they were before but they still have quality players," he said.
"It is a different type of team to what we faced on Tuesday (against Sheffield Wednesday) but nevertheless it doesn’t mean it is going to be easier.
"We know we have to perform all the time now so it is a game I respect a lot."
The Watford boss also reserved a word for Tangerines boss Paul Ince, whom Zola played against many times as a player.
"I don’t know him very well as a manager but I know him as a footballer," the Italian said.
"He was a tough guy all the time, a very good player and he has done well not only in this country but also in Italy where he has a very good reputation."
Watford defender Neuton has suffered another injury setback. Click here to find out more.