Cristinao Ronaldo
Cristiano Ronaldo scored a brace on his 400th appearance for Real Madrid Reuters

Real Madrid star Cristiano Ronaldo has hit back at his critics and is surprised he continually has to prove himself after stepping up again with a double for the Los Blancos in his side's 3-1 Champions League win over Borussia Dortmund.

On a night when Real ended their winless run at Signal Iduna Park, Ronaldo scored a memorable brace after two successive LaLiga matches without a goal. The Portuguese forward then took aim at his critics as he made clear he feels as though he needs to prove himself in every match.

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His goals in Germany on Tuesday ensured the 12-time European champions took a vital three points in their Champions League group, yet Ronaldo cut a frustrated figure.

"It seems that I have to keep showing exactly who I am in every match," he told Atresmedia after his 400th Madrid appearance, as reported by Goal.com.

"I am surprised by what the public thinks of me, my numbers speak for themselves, I am an exemplary professional and I always have a clear mind. The criticism is getting worse."

Gareth Bale opened the scoring with a stunning volley for Madrid at Signal Iduna Park before Ronaldo's second-half double. Ronaldo said Zinedine Zidane's men stepped up, as the Spanish capital club won at Dortmund for the first time.

"Before the game we spoke about how much we wanted to win in Dortmund," he continued.

"We did what the coach told us, the team has been phenomenal, creating opportunities and it isn't easy to score three goals here. We played well.

With Isco and Marco Asensio having both agreed to new contracts with the Spanish champions, attention has now turned to the Portuguese forward, although his current deal is set to run until June 2021.

When pressed on the subject, the former Manchester United star refused to be drawn and suggested such a question should be directed to Florentino Perez, rather than himself.

"It's a good question, these things happen naturally but maybe the president can give a better response than I can," he said.

"I'm happy and I'm doing what I enjoy. People talk about me every day all around the world, I live for football and my family, not for the media.

"Sometimes these stories start in Portugal, in Spain or even Germany, because when you're big business, people talk about you."