Erik ten Hag told a raucous Old Trafford that Manchester United have a "really good chance" of winning the FA Cup and ending local rivals Manchester City's bid for a treble.
United finished the Premier League season by coming from behind to beat Fulham 2-1 on Sunday, a win that secured third place in the table.
Already assured of Champions League qualification after defeating Chelsea on Thursday, United found themselves behind to another west London club when Kenny Tete's early header put Fulham in front.
But David de Gea then saved Aleksandar Mitrovic's penalty before goals from Jadon Sancho and Bruno Fernandes sealed a 2-1 win.
Ten Hag has already become something of a hero to United fans after guiding the club to a League Cup final win over Newcastle in February, a success that ended the Red Devils' six-year trophy drought.
And he insisted they could add yet more silverware when they return to Wembley next week for an FA Cup final where Ten Hag's side will aim to scupper City's hopes of emulating United's celebrated 1998/99 treble of Premier League, FA Cup and Champions League titles all in the one season.
Having thanked United's players and staff after presenting De Gea with the Golden Glove trophy for the most clean sheets in this season's Premier League, United manager Ten Hag turned his attention to the club's supporters.
"If you have our back, I'm sure we have a really good chance to take the (FA) Cup back to Old Trafford," he said to huge cheers from the home crowd.
- 'Give everything' -
The Dutchman insisted there was more to his assertions than blind faith, with Ten Hag telling a post-match press conference: "We beat them in January, but I think Man United in the last couple of years beat City many times.
"So, these players know when they play at their levels that they can compete.
"It's obvious we play against probably -- at this moment -- the best team, but still there is a chance and we have to go for the chance and we have to give everything."
The enduring uncertainty regarding whether United's current owners, the US-based Glazer family, will relinquish control despite initiating a sale process continues to hang over Old Trafford.
But Ten Hag, who said he did not receive the same backing as United's top four rivals during the January transfer window, was adamant sustained financial support was vital to the club's ongoing success.
"The club knows if you want to play top four, compete for trophies in this tough league, then you have to invest," he said. "Otherwise you don't have a chance because other clubs will do.
"We have seen it in the winter that all the clubs around us made huge investments. We didn't and still we made it, so I'm really happy and proud of my team."
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