Oldham took the lead through Tom Pett, whose strike beat goalkeeper Cieran Slicker. Barnet responded late in the first half, with Ryan Glover scoring before new signing Kabongo Tshimanga converted a penalty just before the interval.

Barnet were reduced to 10 men when Nik Tavares received a straight red card following a collision with Kane Drummond. Oldham immediately levelled through Jack Stevens, but Tshimanga scored the winner, converting the rebound after Glover’s cross struck the woodwork.

Brennan said: “We were atrocious in the first half. I was angry about our lack of competitiveness, but the lads showed grit and character in the second half.

“We made a tactical change, putting two players up front late in the game, and it worked.

“Kabby [Tshimanga] made a huge difference – he’s made sacrifices to join us, and the winning goal epitomises his impact.”

On the red card, Brennan added: “There’s no way anyone can be 100 per cent certain that’s a red. Slicker was out of goal, and it could easily have been a yellow. You can’t predict that.

He concluded: “Not many managers would be brave enough to throw two players up front, but it made a huge difference.

“We have to be better in the first half if we want to perform consistently, especially with 11 men.”

Oldham manager Micky Mellon was frustrated as his side’s six-game unbeaten run in Sky Bet League Two ended.

“We’ve got to take our chances,” Mellon said. “As a manager, you wouldn’t often see the amount of chances we had and not win.

“We had five or six opportunities and weren’t good enough to put them away at critical times. That’s why we came away with nothing.

“In football, if you miss that many chances, you can get punished. Barnet had four efforts and scored three.

“We have to be ruthless and punish when we get our opportunities. We didn’t, and that let them stay in the game, even though they were second best for most of it.

“If you come here and play poorly, you should be disappointed. We performed well; it just came down to the most important moments.

“Lack of clinical finishing has been the story of our season. If we want to keep progressing, we have to be more ruthless in front of goal.

“We may free up budget to bring someone in to be a bit more clinical, and we think we know who we want.”