Ange Postecoglou is tipping Brennan Johnson to become a “significant contributor” to his grand design at Tottenham – if he can survive a difficult spell.

Johnson’s stoppage-time winner fired Spurs into the last 16 of the Carabao Cup at Coventry on Wednesday night.

But his celebrations were muted after online trolls forced him to deactivate his Instagram account 48 hours earlier following vulgar social media criticism of his performance in the north London derby defeat by Arsenal.

Two last-gasp goals at the CBS Arena spared head coach Postecoglou’s blushes after his gamble in making eight changes almost backfired.

And the Spurs boss acknowledged £47.5 million Johnson’s bitter-sweet week afterwards, saying: “With Brennan, he comes in, works hard at his game and when you’re an attacking player, you’re always kind of getting measured against certain things.

“If he can get through this period and just be positive and and play like he can, he can be a significant contributor to us and credit to him. He got a good goal.”

Johnson’s late winner and fellow substitute Djed Spence’s equaliser were isolated shafts of encouragement for Postecoglou at Coventry, where the £20m defender finally opened his account for the club more than two years after leaving Middlesbrough.

Spence, 24, said: ““It meant a lot. It was a good feeling – especially to get the team back in the game and then the win.

“I’m happy to be in the manager’s plans, keep moving forward with the team and hopefully we can keep winning.

“I’ve just got to stay ready and be ready for whenever I’m called upon.”