Tottenham boss Ange Postecoglou said his team "work on set-pieces all the time" after a Gabriel Magalhães header in the second-half decided a 1-0 north London derby win for Arsenal and extended the home side's miserable record at defending from free-kicks and corners.

Since the start of last season, Nottingham Forest (23) are the only team still in the Premier League to have conceded goals from set-pieces than Spurs (18).

Postecoglou has repeatedly rejected claims that his team are vulnerable when defending set-pieces, but after Arsenal took advantage of the latest example of Tottenham's defensive frailty, the former Celtic and Australia coach said it is wrong to suggest he doesn't care about the problem.

"I know that, for some reason, people think I don't care about set-pieces," Postecoglou told reporters after the game. "I understand the narrative, but we work on them all the time.

"We held them [Arsenal] well for the most part, but switched off for one and paid a price. They're obviously a very big threat from set-pieces and it only takes one.

"It wasn't just [Cristian] Romero, others switched off too. The delivery was spot on and Gabriel is a threat in those situations.

"We paid a price for it, but you learn from that and you move on. It's my burden to carry and I'm fine with that.

"For me, it's about the finer details of us getting to where we want to be -- for us, the way forward is to try to turn the football we're playing into something meaningful."

Spurs have won just once in the league this season and their recent record under Postecoglou has seen them lose seven and win three of their last 11 league games.

Against Arsenal, Spurs struggled to take advantage of their early attacking threat and Postecoglou said his players need to show more belief.

"A lot of times, with more belief or conviction in the final third we could have taken more of our opportunities," he said.

"We lacked conviction to make the most of them.

"It has been the story of our season so far, we played in their half and created chances but we lack a bit of belief in the final third. That's what we need to fix. It was always going to be decided in moments and they capitalised on theirs.

"We've just got to keep working at it, guide the players in the right way."