Ake, who can play at left-back or in defensive midfield, is highly rated in the Chelsea set-up, and was handed Premier League and Champions League chances last term. He has impressed for the Blues, and Jose Mourinho is big fan of him, but the 20-year-old needs to be playing consistent first-team football if he is to develop.
The newly promoted Premier League side have good links with Chelsea, having taken Nathaniel Chalobah and Josh McEachran on loan in recent years, and the Hornets could utilise that influence to sign Ake.
However, there is one complication in the deal which could prevent Ake leaving Stamford Bridge.
As the Blues sold Filipe Luis, they have just one left-back at the club in Cesar Azpilicueta. This means that they will not entertain any loan for Ake until another left-back is brought in, otherwise the youngster will be used as back-up for the coming season.
Other teams interested in signing Ake
Watford are not the only team to be linked with the defender, although they are the only club to have formally opened negotiations with the Blues.
Chelsea will surely want to send Ake out to a club who can offer him the best chances of playing, and although Watford are the newly promoted side, he would likely only be arriving as cover.
Etienne Capoue and Valon Behrami are first choice defensive midfielders, with Ben Watson as back-up, whilst fellow summer signing Jose Holebas is sure to start the season at left-back - with the likes of Miguel Layun, Ikechi Anya and Daniel Pudil all vying for cover roles.