Mexico coach Juan Carlos Osorio was left concerned by his side's set-piece defending following their 1-1 draw with Venezuela in the Copa America Centenario on Monday.
Jesus Corona scored a brilliant solo goal in the second-half to seal a point at NRG Stadium in Houston, which meant Mexico finished top of Group C.
However, they trailed Venezuela for the majority of the contest after Jose Velazquez had given the South Americans an early lead via an acrobatic overhead kick.
The goal was just the second Mexico had conceded under Osorio since he took over last October, but both of them have come from set pieces.
"We controlled the game almost in its entirety, but the biggest worry we have is the dead ball," the Colombian said.
"In the last 10 games we have played we've conceded two goals, and none of them have been from open play."
Osorio made nine changes to the squad that defeated Jamaica in their second group match, but the 55-year-old insists it did not dent their chances of beating Venezuela.
"We considered the rotations like a principle of life, we wanted to give an opportunity to all of the players because we consider all of them important," he said.
"We picked a competitive group against Venezuela. Here there are not 11 set players every week."
Mexico are likely set to face either Chile or Panama in the quarter-finals of the special-edition centenary tournament.