Watford have signed Tom Dele-Bashiru on a six-year deal after his contract expired at Manchester City.
The central midfielder made one appearance for the Premier League champions, in the Carabao Cup in 2017.
Dele-Bashiru, 19, has represented both England and Nigeria at youth level and scored for the Super Eagles in May's Under-20 World Cup against Qatar.
Meanwhile Watford defender Marc Navarro, 24, has signed for La Liga side Leganes on a season-long loan.
The Spaniard played only two league games for the Hornets after joining from Espanyol last summer.
Find all the latest football transfers on our dedicated page.