Kane injury could be 'massive problem' for Spurs, says Pochettino
Kane was hurt after clashing with United defender Phil Jones in the closing seconds of the match as the visitors dug deep to protect their 1-0 lead at Wembley on Sunday.
Pochettino said he would fret over Kane's fitness, with the 25-year-old set to undergo tests in the next few days while he is set to lose Son Heung-min to the Asian Cup.
"Of course if Harry Kane suffers an injury it would be a massive problem for us. That is my worry, that is our worry," Pochettino told Sky Sports.
"It was a bad tackle in the last moment from a Manchester United player. It wasn't an intention, but it was a bad tackle.
"There's swelling now, we need to assess in the next few days. I hope it's not a big issue but he was limping off the pitch."
Pochettino hailed Tottenham's second-half performance as among the best in his tenure at the north London club, despite Marcus Rashford's first-half winner leaving them nine points adrift of Premier League leaders Liverpool.
"In four-and-a-half years, that's the best performance I saw Tottenham play," Pochettino told reporters. "The second half is one of the best performances I've seen from my team. I thought it was amazing."