Ronaldo is set to win his 100th Portuguese cap in the World Cup qualifier against Northern Ireland at Porto's Dragao Stadium, and few would bet against him marking the occasion in style.
"I have played a handful of times against him but maybe he has gone another level since his days in the Premier League, and maybe he can go further," said Hughes.
"He has gone and become just as successful in Spain and maybe there's more to come from him.
"I don't think he has peaked, believe it or not. He is still going and appears to be getting better.
"Lionel Messi and Ronaldo are the two who stand out as the best two in the world."