The defender - starting at right-back on this occasion - powered home a header from Dean Marney's corner in the 40th minute at Stevenage Borough.
But we held the lead for only five minutes as Watford equalised with the move of the night, a one-touch counter-attack swept home by Jason Norville on the stroke of half-time.
Clear-cut chances were few and far between in a scrappy second half.
Clive Allen's options were slightly reduced with protecting players for possible first team duty on Wednesday against Charlton and the Youth Cup quarter final coming up - also against Watford - on Thursday. Lee Barnard, Marton Fulop, Rohan Ricketts, Jamie Slabber and Johnnie Jackson are currently out on loan.
The first real chance of the game came on six minutes when Marney was hacked down on the edge of the area by Gunnarsson. The midfielder elected to take kicking duties himself and, from a central position, floated his effort just over the bar.
You could detect a determination to make amends among the young side following last week's disappointing reverse at Portsmouth, which followed a very good performance - albeit a losing one - to league leaders Charlton two weeks previously.
Goran Bunjevcevic provided the only real experience in the side in the absence of Sean Davis, who has been feeling unwell and missed out on selection. Watford fielded a young side, with the exception of Gunnarsson and goalkeeper Chamberlain, but appeared a big, physically strong side - which could be a useful pointer for our under-18 coaching team.
The visitors did have the ball in the net on 15 minutes through Coleman, but from an offside position as the assistant's flag quickly confirmed.
We nearly took the lead ten minutes later when a clever ball from Yeates set Dilevski away inside the area and it took a good save from Chamberlain to divert his effort wide. A clever corner from Marney then found Yeates on the edge of the area and, when his shot was charged down, a clear opening emerged for O'Donoghue to take aim but was misfired over the bar.
Chamberlain had to be alert again after 34 minutes when Dilevski fed Yeates in the inside right channel of the area, Yeates drove low towards the far post but the keeper got down well low to his right to palm the ball away.
We took the lead after 40 minutes and it was no surprise to see it come from a corner as Marney swung the ball in from the right and O'Donoghue rose unchallenged to head in off the post from 10 yards.
But Watford struck back in style just before the break. Young played a lovely give and go with Coleman, flicking the ball around the corner and taking the return pass, hitting the byline and crossing low for Norville to side foot home at the near post.
Half-time: Spurs 1, Watford 1
The second half started very scrapily but sparked into life when Malcolm chased down a lost cause, forcing Chamberlain to slice a clearance. From the throw, Marney's blast was deflected wide and then the same player's corner caused problems again to the visiting defence, Bunjevcevic volleying over at the far post.
Bunjevcevic was needed for defensive duties soon after and did well to clear from inside the six-yard box from Norville's dangerous cross.
Coleman might have done better from the edge of the area after 58 minutes, scuffing his shot slightly straight at Forecast and Grant drilled just over seconds later.
The next 15 minutes was scrappy again until Dilevski cut in from the right and drilled a low shot that Chamberlain gathered comfortably.
Academy striker Claude Seanla arrived for his reserve team debut after 79 minutes but Watford threatened next, Young's deep cross heading for Coleman until Limbersky's intervention.
Yeates crafted a half-chance for McKenna with a dart down the right but Gunnarsson's block took any power out of the shot and that was about that.
Full-time: Spurs 1, Watford 1
Spurs: Forecast, O'Donoghue, McKie, Marney (Limbersky, 60), Bunjevcevic, Defendi, Dilevski, McKenna, Yeates, Malcolm (Seanla, 79), Hallfredsson. Unused subs: Button (GK), Riley.
Watford: Chamberlain, Osbourne (Grant, 45), Collins (Mawer 30), Ferrell, Mariappa, Gunnarsson, Darlington, Coleman, Norville, Diagouraga, Young. Unused subs: Kirk, Diafutua, Frost.
Paul O'Donohue's first goal of the season failed to secure a win for our reserves against Watford on Monday night.