LONDON, England -- Pep Guardiola believes that Manchester City's domestic Treble was harder to achieve than winning the Champions League.

City wrapped up the final part of the Treble on Saturday with an emphatic 6-0 victory over Watford, just six days after pipping Liverpool to the Premier League title by a single point.

"It's one of the best seasons I've experienced as a manager, not the best but one of the best for sure," Guardiola said at a news conference. "To be for 10 months playing in all competitions. No team, including incredible teams in this country, have done this and we were the first.

"I love the Champions League, but to do [the Treble] is more difficult than to win the Champions League and we did it.

"It's not easy for 10 months, every three days being there because when you have one bad night you are out of competitions. And especially the way we played today we were a little bit short of energy but that's normal."

City were ruthless against Watford as they equalled the record FA Cup final winning margin set by Bury more than a century ago in 1903.

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Raheem Sterling scored twice and looked to have become the first player to score a hat trick in a final since 1953. But City's second from Gabriel Jesus crossed the line just millimetres before Sterling could claim the goal, although it wasn't officially given to the Brazilian until more than 30 minutes after full-time.

"I've disputed it!" Sterling said. "What can we do?

"The boys were brilliant today and my goals just added to the win. Everyone was fantastic.

"Credit to all the boys today. It's been a fantastic year."

Sterling, whose boyhood home was in view of the Wembley Arch, added: "Growing up here, growing up seeing this get built, it's a dream to be on this football field and winning trophies. It's a massive dream come true."

Teammate Bernardo Silva said that there will be no let-up next season and warned City's rivals that they can get even better.

"There's always space for improvement, and that's what we will try to do," he said.

"Next season we'll try to get better and we'll try to win even more titles, to be even better, to control more of the games, to have more possession, to create more chances to score more goals. We'll work on that.

"To win all the massive competitions, first time any team has done it, it's amazing, what a team this is. The fans were amazing this season as well, they pushed us this far.

"Now it's time to rest and time to celebrate. Next season we will try again."