Portugal's Nani has backed his team mate Cristiano Ronaldo to increase his goal tally in the European Championship and to guide his side to the latter stages of the competition in France.

Ronaldo, 31, rediscovered his form against Hungary on Wednesday after a slow start to the tournament, his two goals saving his side from a surprising group-stage exit in a thrilling 3-3 draw.

Away from football, Ronaldo, who became the first player to score at four separate European Championships, has also been embroiled in controversy, being caught on camera throwing a reporter's microphone into a lake.

"Everyone knows Cristiano and what he can do at any time, in any minute in a game. I am 100 percent sure he will go on and score more goals now," Nani told reporters in France.

"No one can say anything against him. He is a fantastic player. He showed it again against Hungary when everyone was talking about him - he has shut them all up now," he added.

"I think Cristiano (Ronaldo) has always been there, always playing well for us throughout the tournament.

Portugal have laboured into a round of 16 clash against Croatia on Saturday, and despite being winless in the tournament, Nani said the belief in the squad was still high.

"Any team we play, we must believe we can win so it doesn't matter who we will face now," he added.

"It will be difficult against Croatia. They have one day more than us to rest but we are professional, so we will get a quick rest and prepare for the game."