Alfie Mawson is due to undergo a medical on Tuesday ahead of a proposed £20m move from Swansea City to Fulham.
The deal is believed to be worth an initial £15m, with a further £5m dependent on appearances.
Only two weeks ago, the Swans were asking for around £25m for Mawson after enquiries from both West Ham and Burnley, but it appears they did not want to allow the deal to rumble on towards the transfer deadline as happened a year ago with Gylfi Sigurdsson’s move to Everton.
Kyle Naughton, Federico Fernandez and Jordan Ayew also face uncertain futures at the Swans with less than two weeks left of the transfer window.
Mawson, 24, is still to agree personal terms with Fulham, who have been busy recruiting and renewing contracts ahead of their return to the Premier League.
The central defender played in every Premier League game for Swansea last season, but was unable to help save the club from relegation to the Championship.
Signed from Barnsley for £5m in August 2016, Mawson thrived after an unpromising start and made 65 Premier League appearances in two seasons.
He also made six appearances for the England U21 side, and was on the bench for the senior team in friendlies against the Netherlands and Italy in March.
As Mawson leaves, Swans manager Graham Potter has agreed a £3m deal rising to £4m to sign Manchester City youngster Bersant Celina.
Potter has been trying to sign the forward for a number of weeks after his impressive stint on loan in the Championship with Ipswich last season.
The 21-year-old Kosovo international, who has made four first-team appearances for City, scored seven league goals in 35 appearances with the Tractor Boys.
He memorably had to fish his shirt back out of the crowd last October after throwing it to his supporters in celebration at scoring a late winner at Burton.
Barry McKay is also set to arrive at the Liberty Stadium in a deal worth £500,000 with Potter seeing the Scottish winger as a replacement for Andre Ayew, who has joined Fenerbahce.
