Son Heung-min has brandished Tottenham’s five-match winless run as “unacceptable” but eased fears over his own fitness.

Spurs suffered a 2-1 defeat at home to West Ham on Thursday night despite taking the lead through Cristian Romero’s 11th-minute header in the London derby.

It was the fifth match in a row Ange Postecoglou’s team had taken the lead, but failed to hold on for victory, which has set an unwanted Premier League record.

“You are winning five times in a row and then you lose that game like that, it is just unacceptable,” captain Son told SpursPlay.

“I am angry because it shouldn’t be happening. Five times in a row is just unacceptable and I think we are soft.

“This shouldn’t be happening and I love them as boys, I love working with the guys, but it shouldn’t be happening.

“In the Premier League 1-0 is never enough, 1-0 is never enough. The players should know and I should know as well.

“We had the chance to kill the game and we were just soft when we play the final third passes or even someone makes good runs and we don’t find it.

“We have to be ruthless and I also feel the responsibility. It was very sad that the fans were turning around and going home. They didn’t look very happy so a big, big sorry and yeah I take responsibility.

“Every single player; young player, experienced player, good player, superstar, you have to take responsibility and move on stronger.”

Son failed to finish the match with West Ham after he was substituted in the 88th minute.

Tottenham’s top goalscorer limped off after a blow to the back, but was hopeful of being fit for Sunday’s visit of top-four rivals Newcastle.

He added: “Yeah I hope so. I had a big kick on my back, in the bone so we’ll see. I didn’t have time to assess so we’ll see what happens.

“Look, we have to bounce back as strong as ever and it is another home game.

“I know it sounds crazy five games in a row. I hope it was a good lesson and look we have to take the loss and there is no time to regret what we done.

“There is no time to regret so we have to move on, put the chest out, take the responsibility and Sunday we have to make a big step forward.”