Pep Guardiola has promised Sergio Aguero and Vincent Kompany will still be at Manchester City next season.
Aguero scored twice to take his season's tally to 33, the best of his City career, and skipper Kompany was also on target in the 5-0 rout of Watford.
The future of both Etihad stalwarts has been in doubt, with Aguero briefly dropped earlier this term for Gabriel Jesus and Kompany enduring another injury-hit campaign.
But City boss Guardiola insisted: " They will be at Manchester next season.
"They have improved a lot. Vincent played eight or nine games in a row and we saw something special with him, so I can imagine when City (last) won the league one of the reasons was Vincent.
"Sergio helped us a lot. But we have to find him a better solution to score goals, not to depend on Sergio."
However, Guardiola refused to comment on the future of City's out-of-contract players, including Yaya Toure, Bacary Sagna, Gael Clichy and goalkeeper Willy Caballero.
Guardiola had a long exchange with midfielder Toure after substituting him at Vicarage Road, but would only reveal: "I thanked him for what he has done this season. An outstanding performance."
The hammering of the Hornets secured a third-placed finish for City and direct entry into next season's Champions League.
Kompany's fifth-minute header, Aguero's quickfire double and Fernandinho's strike put them four up by half-time before Jesus added number five.
But Guardiola warned it would take the club "decades" before they can hope to catch European heavyweights like Real Madrid and his old side Barcelona.
"Money is not enough - when Real and Barca want a player, other teams cannot compete," he said.
"To compete with Barca and Real we need time, we need decades to be there."
It was not the send-off Hornets manager Walter Mazzarri had wanted, having been informed he was surplus to requirements last week.
The Italian's final teamsheet included no centre-halves - due to injury and suspension - and two goalkeepers on the bench alongside skipper Troy Deeney.
"Look at the players, we had absolutely no defenders," Mazzarri said. "I would like to see which team could do better."