The Bees fell to a defeat at Gander Green Lane but the main concern will be with goalkeeper Aymen Azaze who was stretchered off in first half stoppage time.
The high flying hosts started the better of the two sides, albeit they didn't create any clear openings in the early stages at Gander Green Lane.
The Bees first sight of goal came on 16 minutes as Ephron Mason-Clark combined with Courtney Baker-Richardson before our number 27 saw his strike from eight yards charged down by the U's backline.
The game continued to be an open affair, with the best chance falling to Sutton just before the half-hour mark as Donovan Wilson fired inches wide of the post from 18 yards after a swift U's breakaway.
Meanwhile, up the other end, the in-form Mason-Clark was Bassey's most threatening man in an opening 35 minutes of very few chances.
Matt Gray's side continued to pressure the Bees and were the next to go close as Harry Beautyman's cross just evaded the on-rushing Omar Bugiel.
The half-finished on a very concerning note as goalkeeper Aymen Azaze was stretchered off after colliding with boot of Bugiel whilst making a very brave stop. He was replaced by 16-year-old scholar James Callan who came on to make his Barnet FC debut.
The U's started the second half brightly and had a succession of corner kicks which were dealt with well by the Bees backline. But they had a golden opportunity as Beautyman broke clear on goal, only for young 'keeper Callan to make a tremendous stop at the Sutton top scorers feet.
The Bees were next to have an opening as Lee Vaughan played a brilliant pass through to Baker-Richardson, the Barrow loanee rounded the 'keeper but the U's defence did enough to stop him shooting into an empty net.
Sam Beard then won the ball high up the pitch before firing an effort narrowly over the bar, as Bassey's side looked to stamp some authority on proceedings.
The Bees then had a golden chance with 23 minutes left on the watch, as Vaughan's quick free kick found Tomi Adeloye through on goal but he couldn't get it under control.
We were punished just a minute later, as a corner kick was headed against the upright before Bugiel smashed home the rebound leaving Callan with no chance.
The Bees tried to respond with the introduction of Michael Petrasso but despite some set pieces and crosses into the box they couldn't quite fashion an opening as the clock ticked past 85 minutes.
Bassey's side through all their effort at it on a difficult evening but couldn't quite continue their unbeaten run.
Barnet: Azaze (Callan 45'), Vaughan, Preston, Richards-Everton, Beard, Kefalas, Skeffington (Petrasso 77'), Taylor, McQueen, Mason-Clark, Baker-Richardson (Adeloye 63')