Portugal looked set for a late win when Cedric Soares scored with a deflected shot in the 86th minute, but Hector Moreno equalized for Mexico with a header in stoppage time. We have a great chance of winning the Confederations Cup because there are still two [group] games left.
The result leaves hosts Russian Federation top of Group A, following their 2-0 victory over New Zealand yesterday.
"It's not the result we wanted, we had the game nearly won", said Ronaldo, who was voted the man of the match. "There is no reason to be concerned, we have to think about the next match".
After seeing a goal ruled out in the first half after a referral to the video assistants, which caused confusion on the pitch, Vargas' 91st-minute strike was again handled by video technology, although it was to overturn a wrong call from the assistant match official. We played without confidence, couldn't connect two or three passes.
"It was not the result we wanted", the Portugal captain said.
"If we win we'll be close to qualifying so it's not the time to sound the alarm".More news: China-backed AIIB touts growth, sustainability
"If this is going to happen several times during a game, well it's not very pleasant for the players", Cameroon coach Hugo Broos said.
Portugal had an early effort controversially disallowed by the video referees but they eventually took the lead after 34 minutes through Ricardo Quaresma after a mistake by Carlos Salcedo let Cristiano Ronaldo through on goal.
It would have been the first opportunity Ronaldo had to elaborate on reports linking him with a move away from Real Madrid after Spanish authorities accused him of tax fraud.
Pitana and the linesman had initially allowed the goal, which would have put Portugal ahead 1-0 in their Group A opener.
Despite the disappointing end with Moreno's goal, Santos believes a draw was a fair result.
'It was not the result we wanted, the team had nearly won and we suffered in the last minutes, but this is football, ' said Ronaldo, who is under more scrutiny than usual playing for his country after it emerged on Friday he wants to quit Real Madrid and leave Spain as a result of an investigation into his tax affairs.