Ronaldo is still waiting for his opening goal in France to become the first person to score at four consecutive European championship finals.
The 31-year-old is the holder of numerous goal-scoring records, but he has yet to hit the net at Euro 2016, despite 20 chances so far.
Ronaldo set a new Portuguese record with his 128th international cap in Saturday’s goalless draw with Austria – a milestone overshadowed by his penalty miss.
He crashed a 79th-minute spot-kick against the post in Paris having also failed to score in the 1-1 draw with Iceland last Tuesday.
The star that fans either love or hate won few Icelandic friends by slamming their team’s “small mentality” after the draw.
This has been a frustrating tournament for Ronaldo.
His Portugal side has failed to live up to their pre-tournament billing as Group F favourites.
They lie only third in the table behind Iceland and Hungary, who they must beat at the Stade de Lyon to be sure of reaching the last 16.
“Ronaldo is a player who scores a lot of goals and I’m sure he will score in the next game against Hungary,” said Santos.
Portugal had 23 shots on the Austria goal — hitting the woodwork twice — and Santos expects his side to find the net and win ‘ugly’ if need be.
“It was the first time we failed to score during my reign,” said Santos.
“We created so many chances, we didn’t score, but I think we will next time out.
“We’re sad but we have things in our own hands.
“It doesn’t matter if we play better or ugly football.”
Hungary’s defence is not known for it’s generosity.
Since their 8-1 thrashing by the Netherlands in October 2013 — their record defeat — Hungary has conceded just 20 goals in 24 games.
Their 2-0 win over Austria and 1-1 draw with Iceland means they face Portugal top of Group F and in pole position to advance.
And Bruno Alves says Portugal must back themselves to beat Hungary and book a last 16 clash on Sunday in Toulouse as group winners.
“It’s up to us to break them down. We need to believe and trust in ourselves, that we are able to beat them,” said the Portugal defender.
Portugal have won all five competitive games against Hungary and their two most recent victories in qualifying for the 2010 World Cup.
Off the field, the Hungarians need to watch their step for the rest of their Euro 2016 campaign.
UEFA are set to announce their punishment on Tuesday after crowd trouble in the draw with Iceland.
In Marseille, Hungarian fans clashed with stewards in the Stade Velodrome and set off flares.
Their captain, Balazs Dzsudzsak, personally appealed for calm during the Marseille match.
He wants to see the same passion against Portugal in Lyon, just not the trouble.
“I ask that everyone continues to support us, but in a way which does not give reason for any possible punishment,” said the Bursaspor winger.
“Only the events on the field will determine how we finish the European Championship.”