Mexico coach Juan Carlos Osorio revealed his side put in more preparation for their victory over South Korea than their shock opening World Cup win against Germany.
A 2-1 success over Group F rivals South Korea in Rostov all-but sealed safe passage into the knockout stages for Mexico.
Carlos Vela opened the scoring with a first-half penalty before Javier Hernandez struck his 50th international goal - Son Heung-min scoring a wonderful last-gasp consolation.
The victory followed on from a 1-0 win over reigning world champions Germany in their opening fixture and means Mexico are set to advance to the round of 16 for the seventh straight World Cup.
While they would have been expected to beat their Asian rivals rather than springing a surprise in their first game, Osorio insists they put more work in to prepare for South Korea.
"I believe that we have played very well," he said at his press conference.
"We have had two good matches and I think we have devoted more attention to this match today with South Korea than our match with Germany.
"Very often, sometimes when you play countries that have less of a footballing history, human beings tend to rest on their laurels a little bit and are too relaxed."
Sweden are the final group-stage opponents for Mexico, with Osorio keen to remain focused on that test after celebrating another World Cup win.
"Every match, we insist on being fully focused and not losing that message. We have received a lot of praise but remain focused nonetheless," he added.
"It is bittersweet because we gave plenty of chances to our opponents. It has been a well-deserved victory, the team performed individually in a fabulous way.
"I think we have earned and deserved this victory and want to celebrate it with all our supporters but then it is back to work, focusing on our next match."
South Korea remain without a point following narrow defeats to Sweden and now Mexico.
They are on an eight-match winless run at World Cup finals but coach Shin Tae-yong was pleased with the endeavour of his team.
"Our players I think played a game that they will not regret," he said.
"All of the players became one and until the last minute they really did their utmost. I really am very grateful that they did their best until the very last minute.
"We don't have a lot of resources but, nevertheless, just before the World Cup we had a lot of injured players and after the end of this game.
"I thought about these players quite a lot. We could have played a better game if those players were with us."