Atletico Madrid defender Kieran Trippier said his side always believed they could stun Liverpool after the Spanish club sent the holders crashing out of the Champions League on Wednesday.
Atletico beat Liverpool 3-2 at Anfield for a 4-2 aggregate triumph in the last 16 second leg.
Having won the first leg 1-0, Atletico were heading out after goals from Georginio Wijnaldum and Roberto Firmino for Liverpool.
But Marcos Llorente came off the bench to score twice for Atletico before Alvaro Morata sealed the extra-time victory.
Former Tottenham right-back Trippier said Atletico never lost faith that they could knock out the Premier League leaders.
"We knew it was going to be very difficult but we needed to stay defensively strong and try and frustrate Liverpool as much as we could. We knew that we'd get our chances if we beat the press of Firmino, Salah and Mane," Trippier told BT Sport.
"Liverpool are very strong at home, I've played them so many times in the Premier League, but we knew we'd get our chances and it was about being clinical in those moments and we were.
"You've seen how defensively strong Atletico have been over the years and we were again tonight. The substitutes that came on made a big impact for us."
Trippier hailed Atletico manager Diego Simeone for setting up his team perfectly.
"The way we play is the way we train. He's like this on the touchline in training, it's a joy to learn from him every day and work with him," he said.
Asked how far Atletico, losing finalists to city rivals Real in 2014 and 2016, can go in the competition, Trippier added: "There are some fantastic teams in the competition. We will focus on ourselves and who knows what will happen at the end of the season."
Llorente, who only had three career goals before Wednesday, said Atletico's fierce will to win was the key.
"We don't have any limits to how much we can go through and suffer," he said.
"We defended with our lives and when we all pull in the same direction, these things can happen."