Mexico coach Ricardo La Volpe bemoaned his side's finishing after they were forced to rely on Iran holding Angola to secure their progress from Group D.
El Tris wasted a host of chances, including a penalty, as they belied their one-man disadvantage to push Portugal all the way in Gelsenkirchen.
It mattered little as Angola's draw ensured Mexico's qualification.
But La Volpe said: "Our main problem is scoring. We even had a penalty and didn't get it in, but we played well."
And the coach admitted he had trouble rationalising his side's failure to convert.
I think we are playing the ball around better than our rivals but we're not scoring enough
He was equally disappointed with his side's finishing following their 0-0 draw against Angolo in their last match - a result that meant they could not relax ahead of their match with Portugal.
But he insisted: "We have the forwards we need, we get to the opposing goalkeeper well, but we must put away our chances.
"I think we are playing the ball around better than our rivals but we're not scoring enough.
"For the coach that is the most difficult thing to resolve."
However, he immediately turned his attentions to Mexico's next tie, saying: "We always knew this going to be a difficult group - every one of the groups is difficult.
"But now we can plan for the weekend and look forward to the next challenge."
Mexico must wait to see if they will face Argentina or Holland in the second round, with the loser of that game in Frankfurt El Tris' opponents.