Lee is being dogged by a troublesome knee injury and is facing a race against time to be passed fit to face Crystal Palace in the Championship opener next month.

"It's a problem I've been dealing with for some months now," Lee told the Watford Observer.

"It meant that I trained very little towards the end of last season and it was just a case of doing enough to get by without aggravating it.

"Being at the start of the season I don't want to go down that road again as it can be tough to hit top form when doing minimal training and the physios have advised against that anyway.

"This, though, means that I'm likely to be a couple more weeks out with this while the swelling goes down and I strengthen the knee, therefore there's a good chance I'll miss the start of the season."