Tottenham must take their 1-0 Europa League defeat by AZ Alkmaar as a "wake-up call" going into their "biggest game of the season", says captain Son Heung-min.

Spurs lost their last-16 first-leg tie in the Netherlands - through Lucas Bergvall's own goal - with a lacklustre performance, and their sole chance of silverware now hanging in the balance.

Ange Postecoglou's side created few clear-cut chances and were fortunate to have only a one-goal deficit to overturn in next Thursday's second leg at the Tottenham Hotspur Stadium.

"It's nowhere near where we should perform," Son told TNT Sports.

"It was very disappointing that we performed like this, including me. It's a big wake-up call because next week is the biggest game of the season.

"We didn't create anything in the first half, sloppiness, not performing the way we should.

"Everyone is very disappointed about the individual performance and the team performance.

"There are no excuses, we were not good enough. It's just 1-0, it's still not finished, and next week we have to be much better."

Former Celtic boss Postecoglou pointed out in September that he always wins a trophy in his second season at a team.

That is true of all his jobs where has been in charge for two full years.

But failure to win next Thursday and that streak will be over. Spurs sit 13th in the Premier League and are out of both domestic cups.

"It was nowhere near the level it needed to be," Postecoglou said of his side's performance in Alkmaar.

"It wasn't great from us tonight, pretty much all facets of the game. We didn't really get to grips with any part of the game. We struggled to gain any momentum with the ball, we weren't as aggressive as we needed to be without the ball.

"I don't think it's a matter of effort or attitude. I don't think it is going out there and not trying, but, like I said, we didn't really come to grips and have the right mindset to tackle an away fixture in Europe.

"You are going to face some pressure when you play away from home in Europe and weather the storm and get to grips with it, but we never really did so that was a disappointment."

Striker Dominic Solanke, a 72nd-minute replacement for Son, went off injured late on his return to action after seven weeks out with a knee problem.

"It looks like a knock, but I haven't really seen it - hopefully nothing too bad," Postecoglou added.