Tottenham star Harry Kane limped off the pitch late in the match after scoring two goals against Everton on Friday night.
Kane scored twice in a 2-2 draw at Goodison Park, with Gylfi Sigurdsson also scoring a pair for the Toffees.
In addition to lamenting more dropped points in his team's top-four bid, Jose Mourinho was left sweating on the fitness of a prized asset after Kane was forced to withdraw in stoppage time.
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Everton were awarded a 91st-minute corner as they pressed for the winning goal, and Tottenham initially breathed a sigh of relief after clearing the ball, only for Kane to crumble to the floor in obvious discomfort.
The England international seemed to roll his ankle after getting into a tangle with Richarlison and Toby Alderweireld, with Dele Alli brought on in his stead for the final few seconds of the match.
What was said?
Mourinho is hopeful that Kane won't be out long, as he told Sky Sports after the final whistle: "I think it is too early, let me be optimistic and believe it is nothing serious.
"He felt something but let me be optimistic and believe he has time to recover. It's obvious he is a very important player for us but I cannot speculate."
Speaking to BBC Match of the Day, Mourinho added: "For him to come out it is not because it's nothing, it's something.
"The next match is Wednesday, the other is Sunday, let's see and let's be positive.
"We all felt the same fears of something that stops him playing Wednesday and especially Sunday, but we will see."
Spurs defender Eric Dier added: "It's always worrying when you see him limping because he doesn't fall over easily, he takes a lot of knocks and gets on with it. But it's early days to see how bad it is."
How many games could Kane miss?
Depending on the severity of the issue, Kane could be a doubt for Spurs' next Premier League fixture at home to Southampton on Wednesday.
Supporters will hope that their club captain can return to full fitness in time for the Carabao Cup final four days later, which will see Mourinho's men take on Manchester City at Wembley.
Should Kane's injury prove serious, the England captain could also be in danger of missing Euro 2020 games when the tournament kicks off in June.
Kane saves Spurs against Everton
Kane produced another stellar performance to bail Tottenham out at Everton, who dominated the game for large periods and showed the greater urgency to win.
The 27-year-old opened the scoring with a trademark finish in the 27th minute, only for Sigurdsson to equalise from the penalty spot four minutes later.
Sigurdsson then put the hosts in front just after the hour mark, rounding off a superb team move, but Kane struck again less than 10 minutes later as he fired a fierce volley into the top corner following a mix-up in the Everton defence.