Crystal Palace have completed the signing of Will Hughes from Watford on a three-year deal.
The 26-year-old, who only had one year remaining on his Hornets contract, moves for a fee reported to be worth £6m but could potentially rise to £10m.
On the signing, Hughes told Palace TV: "Fans want to see players give 100 per cent and that's the minimum I'll give. That's what they can expect.
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"The club are planning for the future and it's exciting times ahead. They're not just planning for the here and now, which is obviously important, but they've got a big project going on here so it's exciting to be part of it."
The transfer is a welcome boost for Patrick Vieira, who has repeatedly called for more reinforcements since the start of the campaign, which got under way with a 3-0 loss at Chelsea on August 14.
While chairman Steve Parish and sporting director Dougie Freedman signed Marc Guehi, Joachim Andersen, Conor Gallagher and Michael Olise in the summer, a forward and another midfielder were priorities for the Eagles, after they released nine first-teamers at the end of last season.
Hughes will provide extra competition in the middle of the park and brings a wealth of experience despite being only 26.
After moving to Vicarage Road from Derby in 2017, the midfielder established himself as a regular for the Hornets in the top flight and played a key role in their promotion from the Sky Bet Championship last term.
Having turned down a new contract in the summer, Hughes trained with the under-23s in pre-season.
The Eagles have also been linked with a move for Arsenal forward Eddie Nketiah - although there is a gap in their valuation of the striker and the Gunners' asking price of around £20m.
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