The Chelsea shot-stopper was in awe of the 27-year-old's talent after Czech Republic's defeat on Thursday, as he felt that the Seleccao deserved to run out winners.
The Real Madrid ace powered a header past the custodian on the 79th minute to send Paulo Bento's men to the semifinals in a match which was largely dominated by the Seleccao.
Speaking after the match, Cech admitted Portugal was the worthy winner and made no secret of his admiration for Ronaldo - whom he faced many times in England when the 27-year-old was at Manchester United.
"This is a not a good feeling for us tonight," he told reporters after the game. "We lost, they were better and deserved to win.
"Ronaldo is one of the two best players in the world, and he proved it with that header. He is truly hard to stop."
Portugal will face either Spain or France in the last four, which will be played out on June 27.
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