While the Croatians romped into the tournament's business end with a 2-1 win over holders Spain, the Portuguese came from behind three times in Wednesday's rip-roaring 3-3 draw against Hungary at Parc OL.
Their talismanic forward Cristiano Ronaldo, subdued in the 1-1 tie with Iceland and a goalless stalemate against Austria, rediscovered his scoring touch with two fine second-half goals which saved Portugal from an early exit.
Santos was confident that Ronaldo, who became the first player to score in four European championships, would thrive as Portugal aim to win "a series of finals" on the road to what would be their maiden title.
"Ronaldo is a scorer and a winner, he plays up front and feeds on goals," Santos said after the Real Madrid hitman was voted man of the match against the Hungarians.
"I am sure this performance will boost his confidence in our bid to win the competition.
"Everything is different now because every game that follows is like a final, there is no room for error. We want to come out on top in all of them and go all the way."
"We have to strike the right balance between defence and attack because when we come forward we leave too many gaps at the back, as our group stage results show."
The Croatians, who came from behind to beat Spain with a makeshift team, left their coach Ante Cacic spoilt for choice after reserve striker Nikola Kalinic and several other fringe players shone.
Kalinic enjoyed a rare start instead of the towering Mario Mandzukic and repaid the faith with a sublime equaliser before Ivan Perisic netted a late winner.
"We could have done with easier opposition than Portugal in the last 16 but if we play like we did in the group stage, we have a great chance of progressing," Kalinic told a news conference at Croatia's Deauville base.
"We are one of the best teams here and if our midfield wins the battle in the centre of the pitch, we should win."
"This is the present generation's chance of a lifetime and we will only be remembered if we do something big here."
(Writing by Zoran Milosavljevic; Editing by Ian Chadband)
