Mauricio Pochettino hopes Dele Alli was not seriously hurt as Tottenham earned a dramatic 2-1 Premier League win at Fulham but conceded the midfielder's hamstring injury "doesn't look great".
Alli headed Spurs level at Craven Cottage on Sunday, cancelling out an own goal scored by striker Fernando Llorente, but he could not complete the match.
The England international appeared to pull his hamstring and had to be replaced by Georges-Kevin Nkoudou, who created the 93rd-minute winner for Harry Winks.
With Harry Kane already sidelined until March, Spurs can ill afford Alli to be ruled out for any stretch of time, but Pochettino said he will wait for test results.
"We all see that during the action he suffered an injury in his left hamstring," Pochettino said to Sky Sports.
"Now we need to assess him in the next few days.
"I hope it's not a big issue, but we know when this type of injury appears we need to be careful.
"First we need to assess what is going on with his muscle."
Speaking later at a post-match news conference, Pochettino added: "It doesn't look great."
Despite Alli's injury, Pochettino was thrilled with the character shown by his side as they bounced back from a 1-0 Wembley loss to Manchester United last time out.
"I am so excited now, the end was amazing and showed you always need to believe in your team," he said to Sky Sports.
"It was a solid performance, maybe not great. Fulham are a team that needed to win and show their quality and of course we struggled a little bit from set pieces.
"I am happy, because after Manchester United it was a very tough week for us, around the team some negatives but we have turned them into positives today. Today for different players there were massive opportunities to step up.
"I think it was fantastic for Nkoudou, I think his first league game it was important. In the 93rd minute for us to build from the back and for Winks to arrive in the box. That is the belief that we love to see from the players."
Even Llorente, deputising for the injured Kane and wasting a string of fantastic chances on top of the own goal he scored, earned Pochettino praise.
"He was good, I am so happy with his performance," Pochettino said of the striker, who was making his first Premier League start of the season.
"I think his performance was very good, he helped the team in the 93 minutes. Of course he has a few clear actions to score. That is the most important.
"It was tough for him to compete but he deserves now the opportunity. He's very professional and a very good player."
