Portugal goalkeeper Diogo Costa said he had the best game of his life against Slovenia on Monday as he saved three penalties to send his team into the Euro 2024 quarter-finals.

After a goalless draw over 120 minutes of the last 16 clash in Frankfurt, Porto goalkeeper Costa produced three saves to thwart Slovenia's three takers as his team claimed a 3-0 shoot-out win.

Cristiano Ronaldo, who missed a penalty in extra-time, converted in the shoot-out along with Bruno Fernandes and Bernardo Silva for Portugal, who face France on Friday in the last eight.

The 24-year-old also made a vital one-on-one save with his foot in the second period of extra-time when Slovenia's Benjamin Sesko bore down on his goal following a defensive error.

"I think this is probably the best game of my life, maybe the game I was most useful in," Costa told reporters.

"I just went with my gut, of course we analysed the shooters, but players change their minds, and they change the way they shoot.

"I had to go with my gut, that's what I felt. I am very, very happy, and I am very excited to help the team."

Costa said he tried to anticipate what Sesko was going to do for his crucial save near the end of extra-time.

"I thought 'I need to stop this, I'll give it my best effort'," he explained.

"I tried to read his body language and thankfully I managed to help the team, which was the key thing."

Costa was pleased Ronaldo dusted himself down and scored after his 105th-minute penalty miss that left the superstar striker in tears.

"We all felt we needed to keep believing -- myself and Cristiano, everybody makes mistakes, but the most important thing is what we do after these mistakes," added Costa.

"We need to believe in ourselves and that's what we did. And now we're all very happy and all friends."

Selecao coach Roberto Martinez said Ronaldo's emotions showed how much he still cared in his sixth European Championship, despite a long and illustrious career.

"Those emotions are incredible for someone who has done so much, that's why I thank him... only the penalty takers can miss penalties," said Martinez.

"I was certain he had to be the first taker (in the shoot-out) and show us our way to the victory.

"Everyone is very proud of our captain. He gives us all a lesson, to have real high standards and never give up."

Martinez also hailed Costa, saying the shot-stopper is a "very well kept secret in Portuguese football".

"I've worked with a lot of goalkeepers and he's up there with the best," said Martinez.

"(The key is) his maturity, his experience, and we now get to benefit from his performances."