Lucas Moura’s 85th-minute equaliser earned a priceless point at Barcelona, as Spurs completed an unlikely turnaround in Group B having collected only one point from their first three games.
They needed to match or better Inter Milan’s result at home to PSV Eindhoven and had faced elimination when Mauro Icardi cancelled out PSV’s early goal.
Moura’s goal swung the advantage back in Spurs’ favour but an agonising wait followed before it was confirmed Inter had failed to find a winner against the group’s bottom side.
“I am so happy for the fans – this is a massive, massive achievement for the club,” said Pochettino.
“We suffered because when we finished the game we did not know the result at Inter. It was two very difficult minutes, but in the end of course we were so happy. It’s so important for the club.”
The Premier League side had gone behind to Ousmane Dembele’s early strike but then peppered Barcelona’s defence with wave after wave of attacks, with both Harry Kane and Son Heung-min going close.
They finally made the decisive breakthrough five minutes from the end when substitute Moura, who moments earlier had a header cleared off the line, fired in.
Spurs become only the eighth side to qualify from the group stage after claiming only one point from their first three games.
Meanwhile, Liverpool boss Jurgen Klopp said he “could not be prouder of a team” as Mohamed Salah’s goal and Alisson’s brilliant late save earned a place in the Champions League knockout stage with victory over Napoli.
The Reds needed to win with a clean sheet or by two clear goals to make the last 16 – and in-form talisman Salah obliged by beating David Ospina at his near post in the 34th minute.
Liverpool fully deserved their victory as Ospina partially redeemed himself with fine saves from Salah and Sadio Mane, with the latter and Virgil van Dijk also missing clear chances to extend the home side’s advantage.
The clean sheet was the key, however, and Liverpool survived a huge scare in injury time when Alisson made his crucial save from Arkadiusz Milik in a rare Napoli opening.