Mauricio Pochettino fears Kieran Trippier has developed a persistent groin problem due to his exertions at the end of the World Cup after the right-back limped off against Southampton.
Trippier, who had been out of action since Nov. 10, played from the start in Wednesday's 3-1 victory over the Saints and played a key role in Spurs' third goal -- but he had to leave the field in the 87th minute.
"I think it's the same problem -- the same problem that started in the World Cup," said Pochettino in a post-match news conference. "If you remember the semifinal against Croatia, when he left the pitch, I think to play after three days against Belgium, I think maybe it affected [him] a little bit. Now he's suffering in that situation.
"In situations like today when the pitch is not in a good condition, this area -- the groin -- suffers more when the pitch is different.
"It's a thing that we need to care a lot for him, protect him. He needs to work a lot to protect and sort that problem. It will be a long period for him suffering this type of problem.
"When I was in Argentina as a 19-year-old I suffered and it is an area that is difficult to sort out. But I don't believe it's a big thing. It's only he needs to start to accept that situation and live with sometimes some pain, and play."
Tottenham were always in control against Southampton, having taken the lead through Harry Kane's ninth-minute strike, and were 3-0 up 10 minutes into the second half. But they then took their foot off the gas and their visitors ended up having 18 shots -- five more than Spurs -- with five on target.
"I was saying that maybe we conceded more chances in the last 30 minutes than in 90 minutes against Arsenal," said Pochettino. "With 3-0 maybe we drop a little bit in our concentration. I think we start to think the game was over and always it's so dangerous when there's so much time to play. In the end [Hugo] Lloris was man of the match.
"In the same way I try to understand, it was a tough evening, difficult to play the three emotional games we played last week [against Chelsea, Inter Milan and Arsenal].
"You pay. It's not easy to feel fresh in your legs or your mind -- whether you play or not play. Players that don't play are the same.
"For me the most important thing is to keep going -- 33 points, third in the table, and I think a fantastic Premier League season."
Wembley was almost two-thirds empty as only 33,012 people turned out at the 90,000-seater arena, but Pochettino said: "I think we cannot ask more from our fans.
"Of course it was a difficult evening, but it is for the players and fans and we cannot ask for more.
"After the defeat to Arsenal you can understand the disappointment of the fans and this evening, to come here to Wembley is so tough.
"I hope in the future to provide better performance and make happy our fans and [make] our fans want to come here to share the happiness. But today there's nothing to say, because to come to Wembley was tough and I understand why Wembley wasn't great in the atmosphere."