Portugal and Mexico both made changes as the hour-mark approached in a bid to find that killer second goal, with Dos Santos and Andre Silva coming on and as the clock ticked, the game began to get stretched.
Portugal saw an early goal by Pepe disallowed for offside courtesy video refereeing.
They wouldn't keep their lead into half-time though, Javier Hernandez drawing Mexico level just before the interval.
The match should prove to be one of the best this weekend and one of the best in the group stage of the Confederations Cup. Both are tucked in a favorable Group A, with No. 95 New Zealand and the host country, No. 63 Russian Federation. New Zealand is at the bottom of the group with no points.
Quaresma had a golden chance to double his tally six minutes later when Ronaldo set him up with a brilliant back-hell but his finish was just wide of the Mexico goal, much to the relief of Ochoa and co.More news: Over 50 Possibly Killed in London Tower Fire, PM May Admits Failings
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He said: "It was not the result we wanted, the team had the game nearly won and we conceded a goal in the last minutes, but that is football". Minutes after coming on, he almost scored a great headed goal but Ochoa came up with a terrific save.
On Friday, a source close to Ronaldo revealed the Real Madrid forward wants to leave Spain.
Cristiano Ronaldo's initial shot hit the crossbar then Pepe "scored" from the rebound in the 22nd minute. A media circus surrounding their most important player is the last thing required by manager Fernando Santos, who made a point of drawing a line under the topic in his pre-match news conference and did not address it afterward.
"34" - GOAL! Portugal 1-0 Mexico. This tournament will be hard for them to win with a lot of talent in the likes of Germany here but still I will expect them to compete in this game.
Late in the second half, Southampton's Cedric Soares put Portugal ahead with a perfectly straightforward goal, but for some reason there was an age to wait to restart the game as the video assistant wanted to make sure it was a good goal. We know we still have lots of opportunities, there are two games remaining and that's why we're calm.
Mexico weren't down and out though, demonstrating their incredible team spirit to storm back with a stoppage time equaliser, ensuring the two teams took a point each.