Ronaldo ignored swirling speculation over his Real Madrid future to provide an assist for Ricardo Quaresma’s first-half opener in Kazan in a man-of-the-match display.
Javier Hernandez levelled for Mexico shortly before half-time although Cedric Soares looked to have earned Portugal victory four minutes from time.
But Hector Moreno’s late header denied Portugal the win in their first match in Group A.
“I first of all thank the fans for voting for me, but it’s not the result that we wanted. Our team practically had the match won and we conceded a goal in the final minutes. That’s football though,” Ronaldo told FIFA TV.
“The team still firmly believes in itself. We know we still have lots of opportunities, there are two games remaining and that’s why we’re calm. Now we have to think about the next match because we must win.
“If we win we’ll be close to qualifying so it’s not the time to sound the alarm.”
Ronaldo reportedly wants to leave Real after being accused by Spanish prosecutors of defrauding the authorities of 14.7 million euros ($16.5m) in tax through offshore companies.
Spanish sports daily Marca wrote Sunday that Real coach Zinedine Zidane interrupted his holiday to call Ronaldo in a bid to persuade his unsettled star not to quit the club.
The 32-year-old walked through the post-match mixed zone without talking to reporters in Russia.
Portugal play the hosts in Moscow on Wednesday before completing their group fixtures against New Zealand in Saint Petersburg on June 24.
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