Their advantage would last just eight minutes, as Mexico’s record goalscorer Javier Hernandez met a right wing cross with a diving header to pull his team level on the verge of half-time.
Cristiano Ronaldo was kept out of the media spotlight in the wake of Portugal’s 2-2 Confederations Cup draw on Saturday.
However, with two teams qualifying for the semi-finals from the four-team pool and Russian Federation up next, Ronaldo is confident the European champions can quickly improve their fortunes.
The FIFA Player of the Year, who had scored 11 goals in seven games coming into Sunday’s encounter, was perhaps not as influential as usual but was still named man-of-the-match. His goal in the 91st minute was also referred to the video assistant referees – presumably to check on another possible offside – but it stood.
“It was not the result we wanted”, said the four-time Ballon d’Or victor.
It took at least 30 seconds for Vargas’s goal in second-half stoppage time to be confirmed after Alexis Sanchez was judged not to have been in an offside position earlier in the move.
Play continued for about 10 seconds until the ball got to Nani and he scored from inside the area after a shot by Ronaldo hit the crossbar. The strike was ruled out following advice to referee Nestor Pitana from the video replay team.
Portugal did nudge back ahead as time was starting to run out, Cedric Soares making it 2-1 with four minutes of normal time remaining.
The second half became more defensive as both sides wanted to protect what they had, and Ochoa produced a huge save from substitute Andre Silva, whose header was heading for the bottom corner, only to be brilliantly scooped away one-handed by the Malaga stopper.
The tournament is traditionally used as a warm-up for the following year’s World Cup and features the home nation, the winners of six continental tournaments and the reigning FIFA World Cup holders.
“Now we have to think about the next match because we must win”.
The victory gave Chile a ideal start to their maiden Confederations Cup campaign, after they qualified by successfully defending their Copa America title previous year.