Premier League newcomers Fulham have signed defender Alfie Mawson from Swansea City on a four-year contract in a deal that could cost up to £20m.
The 24-year-old featured in all of the Swans' Premier League games last season, earning a call-up to the full England squad.
Barnsley will also receive a payment due to a sell-on clause.
"I'm excited by the project going on here and I can't wait to get going," said Mawson.
"The football being played last season was lovely on the eye but also effective and I can't wait to be a part of it.
"I'm excited to be a part of this great club moving forward and to help achieve success in the Premier League."
Mawson's career began at Brentford, while he also had loan spells with Luton, Welling and Wycombe before joining Barnsley.
He moved to Swansea in 2016 and was a mainstay in the club's defence last season, but could not prevent their relegation in May.
Fulham have already signed Serbia striker Aleksandar Mitrovic for a reported £22m, Spanish goalkeeper Fabri from Besiktas, German forward Andre Schurrle on loan from Borussia Dortmund, as well as Ivory Coast midfielder Jean Michael Seri and French defender Maxime le Marchand from Nice.
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