The Spaniard, who had felt under the weather this week, said: "I want to learn and it's important. I'm ready, of course, but I will rest now.

"I need rest, I will come back to Spain for 10 days and after I promise to come back with full power, big energy and with very good things for the future.

"I need to learn about the Premier because I want to know all it does but when I come back, I am sure I am ready."

Xisco fielded a much-changed XI and gave opportunities to some of the players on the fringes, including Gray who scored only his fifth goal of the season when he chested home Ken Sema's cross in the 56th minute.

Isaac Success added gloss to the score with a wonderful finish two minutes from time when he smashed home on the half-volley.

Troy Deeney was on the pitch by that point for his first appearance since February after he recovered from an Achilles injury to appear as a substitute.

Watford's captain is out of contract this summer but was given a big vote of confidence by his manager.

"We have a lot who played in the Premier League," Xisco added. "I have luck with our squad because sometimes I can only pick 11 players and if you asked me 'is Troy Premier League?' Everybody knows Troy is a player for the Premier League."

Another big personality present for the final-day win was pop star and former club chairman Elton John, who watched from the stand at Vicarage Road and spoke with the players before the game.

"He is a big legend, I think he put the name of Watford in all the world and it's important when the big personalities are coming in the dressing room and show everyone what is the passion for the club," Xisco said.

"About my last four months, I can only say congratulations to the players. I am lucky because everyone in the training ground, everyone here worked so hard for our amazing goal."

The season is not over for Swansea, who finished fourth and discovered they will take on Barnsley in the play-offs later this month.

It was the visitors who started the strongest of the two teams but they failed to make the most of their chances in Hertfordshire.

Boss Steve Cooper said: "Congratulations to Watford, they've done brilliant this year in getting promoted in what has been an incredibly tough season.

"I didn't think we deserved to lose, but at the same time we didn't do enough to win it. We got into loads of great positions to threaten the goal and we didn't and they did with the two goals, which was the difference.

"But I said to the players I liked so many parts of the performance apart from the final bit, which is often the most important. The stats behind the game show that so something to focus on going into a couple of big games in the semi-final."