Lewis Mansell was again the hero as he bagged the winner for the second consecutive away game to send Rovers top of the Premier League Cup.
Mansell struck with 17 minutes remaining to defeat Hayden Mullins’ Hornets at Wealdstone Football Club on Monday evening.
Coach Damien Johnson again handed a run out to trialist Chiori Johnson, with the winger starting on the right.
Fellow trialist Okera Simmonds began as well having come off the bench in the win against Reading last time out.
Willem Tomlinson returned to the XI after coming back from a two-game suspension, but Darragh Lenihan wasn’t involved having travelled with the first team to Portsmouth.
It was Rovers who started the brightest, with Sam Howes denying Tomlinson from handing the visitors the lead with an excellent stop just eight minutes into affair before denying Charley Doyle and Joe Grayson soon after.
Watford’s only notable effort was Dennon Lewis’ strike flying over the upright in a half which lacked too many chances, mainly down to a poor pitch.
The Hornets did improve after the break, with David Sesay smashing a free kick over the bar,
And whilst the game looked destined to end 0-0, substitute Mansell came on to thrash a strike across Howes and in off the post to hand Rovers the advantage.
To their credit, Watford continued to press for an equaliser, but Andy Fisher ensured he’d earn a third consecutive clean sheet as Johnson’s charges ensured another victory to top the table.
Watford: Howes, Eleftheriou, Mukena, Ryan, Jones, Sesay, Charles, Stewart (Kaikay 81) Lewis, Pereira, Bradbury.
Subs not used: Tricker, Gartside, S Sesay, Forster.
Rovers: Fisher, C. Doyle, Magjoire, Grayson, Johnson (Hardcastle, 54), Tomlinson, Buckley, Evans, Butterworth, Simmonds (Mansell, 67).
Subs not used: Carter, Albinson, Vale.
Goal: Mansell, 73