Pellegrini’s side are still competing on four fronts in the second half of the season.
But seizing back the Premier League trophy is what the Chilean really craves. With the spectre of Pep Guardiola looming large, Pellegrini is widely expected to sign off next summer.
His hopes for a parting gift will lie on the shoulders of the Argentine striker, last season’s Golden Boot winner.
Aguero has endured a stop-start injury-hit season but his late winner here in City’s comeback victory saw him reach double figures.
When Aguero is at his blistering best, there is no striker in England’s top-flight who can come close to him.
Following his first goal since November 21, Pellegrini said: “Kun is very important to our team.
“He has improved also a lot in his whole performance if you compare it with his last game.
“I think we know he needs three or four games to return to his top performance and for him the goal was important and hopefully he can go on.” While Aguero hitting the goal trail again will be welcomed, more significant was City’s first victory in seven away games.
It’s certainly not title winning form but, despite their struggles on the road, they lie just three points off Arsenal at the summit.
That will send shivers down the spine of their rivals but Pellegrini says he was never concerned by their travel sickness.
“We were not worried,” he said.
“It’s not normal not to win for six games but we were playing well.
“Against Arsenal and against Leicester we played a good game. So I think it was important to keep the trust in the players and I think we did well here.
“I think the most important thing of the team was the character we showed. We were convincing with the way we played.” It could, and perhaps should, have been another devastating setback for big-spending City.
Watford appeared headed for victory when Ben Watson’s 55th-minute corner was flicked into own net by Aleksandar Kolarov.
The visitors looked devoid of ideas and Etienne Capoue missed a glorious chance to wrap up a home win.
That proved pivotal as Yaya Toure fired home a stunning 82nd-minute volley from Kolarov’s corner, before Aguero’s textbook header from Bacary Sagna’s corner two minutes later stole the points.
City defender Sagna hailed stand-in-captain Toure for leading from the front and driving City on for the smash-and-grab win.
“Yaya has been very important to us as a team and we all trust him,” said Sagna.
“He is also one of the leaders in the team.
“He is our captain while Vincent Kompany is away and he scored a great goal – and he scored against Sunderland and Arsenal.
“Of course he will get criticism because two seasons ago he scored 20 to 25 goals and people are expecting him to do the same. He is very important in our system.
“He can’t be on top and score in every single game. But he did it at Watford and has been doing that in the last few games.
“He is not the only one. Last season when we were not performing he was the main target, and it isn’t fair because before that he had a great season and gave a lot to the team.
“We win as a team and lose as a team.” Watford manager Quique Flores knows need reminding of Aguero having worked with him with old club Atletico Madrid.
“He is one of the best players in the world,” said Flores.
“I managed a lot of players but Sergio and David Silva were a little different.” Watford midfielder Watson was upbeat despite cursing City’s late show.
He said: “We have taken four points from four high-profile games either side of Christmas.
“But we believe it should have been more which is a good sign for this club. We have not been blown away in any of them.
“For 80 minutes we felt we dominated the game but that’s what can happen against world class players.”
Asked if City were the favourites to win the title, Flores said: “Yes. I thought so in the first leg (half of the season). I keep thinking the same.”
Gomes (6); Nyom (6), Britos (6), Cathcart (6), Holebas (6); Abdi (6), Capoue (6), Watson (8), Jurado (6) (Guedioura 79); Deeney (6), Ighalo (7).
Arlaukis, Prodl, Behrami, Oulare, Berghuis, Anya.
Hart (7); Sagna (7), Otamendi (7), Mangala (5) (Bony 74, 6) Kolarov (6); Fernandinho (8), Toure (7); De Bruyne (7), Silva (5), Sterling (5)(Navas 61, 6); Aguero (6) (Demichelis 85).
Caballero, Zabaleta, Fernando, Clichy.