Spain winger Bryan Gil, 20 – who only joined last July – has joined Valencia on loan until the end of the season.
Ndombele, 25, joined Tottenham for a club record 60m euros (£53.8m).
Bentancur is a former Aston Villa target and is currently on World Cup qualifying duty with his country.
Meanwhile, Giovani lo Celso is also set to leave Spurs on loan.
Villarreal are targeting Argentina midfielder Lo Celso, 25.
Spurs fans protest outside training ground
BBC Sport’s Alex Howell
It’s been a busy day for Tottenham who have so far secured two signings and let Ndombele leave.
However, that’s not the only thing going on at Spurs at the moment. I’m outside the Tottenham Hotspur training ground where a group of around 50 supporters are protesting against the club’s ownership and board.
They say that there is, and has been, a lack of investment in the playing staff, no accountability and a focus on the corporate side over the football side of Tottenham.