Watford's main priority has been bringing in a winger, with Ismaila Sarr, of Rennes, their top target.
Talks have dragged, but it is hoped an agreement can be struck.
That will likely set Watford back around £25million to £30m, but they have money after selling Dodi Lukebakio to Hertha Berlin for £20m.
Gerard Deulofeu and Roberto Pereyra look set to stay, while the club are adamant they will resist late offers from Everton for midfielder Abdoulaye Doucoure.
Watford’s only significant addition has been centre-back Craig Dawson from West Brom.
They could still add another centre-back, with Bordeaux’s Youssouf Sabaly, Bastos, of Lazio, and South Korean Kim Min-jae all options.
Watford are also hopeful of completing a deal to sign Danny Welbeck on a free transfer following his release by Arsenal.
Watford summer ins and outs
In: Craig Dawson (West Brom, £5.5m); Mason Barrett (West Ham, undisc); Sam Dalby (Leeds, undisc); Bayli Spencer-Adams (Arsenal, free); Tom Dele-Bashiru (Manchester City, free); Callum Whelan (Manchester United, free).
Out: Dodi Lukebakio (Hertha Berlin, £20m); Obbi Oulare (Standard Liege, undisc); Miguel Britos, Tommie Hoban (both released); Michael Folivi (AFC Wimbledon, loan).
