The win came courtesy of quickfire goals from Troy Deeney and Nathaniel Chalobah towards the end of the first half and moved Watford to within a point of second-placed Hull, who face Barnsley at Oakwell on Saturday.
A win for Steve Bruce's side over their lowly opponents would confirm Hull's place in the Premier League next season and condemn Watford to the play-offs.
But Zola said: "I think it will go down to the final day, I hope so.
"In this league nothing is certain, it has been that way all season. Any team can beat any team - as we have seen.
"I'm sure it will go right down until the end, and it will be exciting. I will keep an eye (on the Hull game) but I will also try to relax, of course.
"We have done what we needed to do and now we have to hope that a good result will come from somewhere else.
"I am very proud of my players. I think our performance in the first half was
remarkable, and we also played a very good team.
"It was a great game with some very good football - Premier League football."