(Photo credit: Mike Segar-Reuters via Imagn Images)

After confirming this will be his last World Cup, Cristiano Ronaldo insisted that whenever his final match arrives, he will walk away at peace.

And yes, even if that comes as soon as Monday in Portugal's round of 16 clash with Spain in Arlington, Texas.

'I'm going to be perfectly honest, regardless of what happens tomorrow, Cristiano is going to be 1000% leaving with a clear conscience,' the 41-year-old said at Sunday's pre-match press conference. 'I have given all I could to football. It's my passion to play for so many years. I didn't do it out of need; I'm doing well out of life. It's about passion. I play for the national team, and I love to play football.

'Regardless of what happens tomorrow, I'm not going to exert pressure on myself that I must win.'

That's probably best for Ronaldo's side, who will enter the match as modest underdogs against a Spanish team that is among the oddsmakers' favorites to win the whole tournament.

Portugal squeaked into the last 16 in dramatic and disputed fashion with a 2-1 victory over Croatia, in which manager Roberto Martinez pulled Ronaldo in the 81st minute and was rewarded with Goncalo Ramos' winner in the fourth minute of second-half stoppage time.

After that came the controversial decision to rule an apparent miracle equalizer from Croatia offside even deeper in extra time.

Despite Ronaldo's lack of involvement in the late drama, Spain manager Luis de la Fuente still says his side must be aware of the one-time Manchester United and Real Madrid star, who remains his country's most productive scorer at his sixth World Cup.

'As a footballer, he is someone you have to take care of, he can change a game in the moment,' de la Fuente said. 'It's not that we have to do man-to-man marking, but in certain areas we have to be aware he's there.

'Cristiano has quality and class, and in any moment he can be decisive. I would prefer if he didn't play, of course, but I think he will.'

Both teams have already had slip-ups, with Portugal playing the Democratic Republic of Congo to a 1-1 draw in their group opener and Spain playing to a nil-nil affair to open their tournament against Cape Verde.

Those results looked better as the tournament wore on, with the Congolese putting a scare into England in the round of 32 and the Cape Verdeans doing the same to Argentina.

And while Ronaldo may be in the twilight of his career, his three goals are still a far more productive tournament than that of Spain's 18-year-old starlet Lamine Yamal. He has only one goal through four appearances while gradually increasing his minutes to work back from a mid-April hamstring injury.

Portugal haven't won a match against their Iberian neighbors since a 2010 friendly, though they did defeat Spain on penalties to capture the 2025 UEFA Nations League final following a 2-2 draw.

'I think the game will be very different, not only in a football sense,' de la Fuente said of Monday's clash. 'Our football idea is similar; we like to have the ball. But it's the World Cup and a World Cup is a unique opportunity.'

--Field Level Media