Watford have agreed a £7.5m fee with Newcastle for Daryl Janmaat, according to Sky sources.
The Netherlands international right-back is understood to be on his way to the south-east for a medical.
Sky sources understand that Newcastle will replace Janmaat with Spurs right-back DeAndre Yedlin, who is to undergo a medical with the Tyneside club on Tuesday.
Janmaat signed for Newcastle in a £5m deal from Feyenoord in 2014 and has made 78 appearances for the Magpies.
He has played twice in the Sky Bet Championship this season, against Fulham and Huddersfield, but was left out of the squad for Tuesday night's EFL Cup clash at home to Cheltenham.
Newcastle manager Rafa Benitez said on Monday that the club could sell Janmaat if they received a "fantastic offer" for the player.
Benitez also said: "I told him the other day that, if he is here, he is a player that I like. He is a good professional and I don't have any problem."
Janmaat began his career at Heerenveen before a 2012 move and a two-year spell with Feyenoord.