Goals from Dele Alli either side of half-time and another from Christian Eriksen set Mauricio Pochettino's side up for a famous victory, with Cristiano Ronaldo's late strike not much of a consolation for the Bernabeu outfit.

Tottenham are now guaranteed passage to the last 16, with Madrid still likely to join them given Borussia Dortmund's 1-1 draw at home to Apoel Nicosia in the night's other Group H game.

Although a second defeat in four days, following Sunday's 2-1 La Liga reverse at Girona, has alarmed Blancos fans and pundits, the former Galactico told the postgame news conference at Wembley that he would not overreact to the result or over-criticise the performance.

"We have lost in La Liga and in the Champions League," Zidane said.

"Two defeats in a row. We cannot be happy, or in high spirits. This is a bad moment, but we must keep our heads up always, knowing football is like this.

"I am not worried, and I never will be all year, whatever happens. We played against a better team tonight. We must accept that."

Zidane pointed to his team's inability to convert enough of the chances they made as their main current issue.

"There are moments over a season when you score lots of goals, from few chances," he said. "And other moments when you don't, like recently.

"We did not play a bad game, we had chances to equalise [at 0-1 down]. But the ball did not go in, and they scored three."

A side which had a busy preseason schedule in the United States, followed by UEFA Supercup and Spanish Supercopa games in August, was not ailing physically, Zidane maintained.

"We cannot say we are in bad shape physically," he said. "Different players recover differently, and maybe you might think some players are doing worse than others. but physically we are fine."

Zidane backed his squad, most of whom have at least two Champions League titles on their CVs, to come good before the end of the season.

"We have an experienced team, these players are champions, we are going to turn this around," he said. "The dressing room is not happy, they cannot be happy.

"It is a hard defeat for us today. But it was deserved, and we must accept it. Today is not a good moment, but we have time to change things and know how to do that."

Asked if Tottenham were now realistic challengers for trophy, Zidane did not appear to want to enter a debate.

"Any team [in the competition] can win the Champions League," he said.

"Tottenham are one of those."