Mexico and South Korea will seek a place in the World Cup knockout stage when they meet in Guadalajara on Thursday, with victory guaranteeing progress to the last 32.
The Group A rivals enter the match at Estadio Akron after opening-round victories against South Africa and the Czech Republic respectively.
The expanded 48-team World Cup format, together with the qualification of the eight best third-placed teams, means a win for either side would secure advancement from the group stage.
Co-hosts Mexico comfortably defeated South Africa in their opening match but face a far sterner challenge against a South Korean side packed with quality.
"We have to be very wary of the opponents' attacking transitions," Mexico coach Javier Aguirre said.
"When we are attacking, we can't let our guard down; if there are two Koreans up front, there need to be three Mexicans."
Preparations for Thursday's fixture were overshadowed by an unusual incident after a drone was spotted above South Korea's training ground on Tuesday.
Yonhap news agency reported that a South Korean security officer detected the device, while a Mexican military drone-interdiction specialist stationed at the camp forced it down by emitting radio signals.
Two men suspected of operating the drone recovered the crashed device and left the area. South Korea coach Hong Myung-bo described the incident as "unfortunate" but said it had not significantly affected his team.
Hong is also preparing his players for a challenging atmosphere against the host nation.
"We fully understand that it's going to be a match with the home team, and we know that that's going to give benefits to the home team," Hong said.
"But my players have experienced such matches before, so it will be different tomorrow, and we need to control the rhythm and the flow of the match."
Elsewhere on Thursday, Switzerland face Bosnia-Herzegovina in Group B after their opening draw with Qatar, while co-hosts Canada meet Qatar in Vancouver.
Bosnia-Herzegovina coach Sergej Barbarez has urged his players to draw inspiration from their qualifying campaign, during which they eliminated Italy in the play-offs.
Barbarez dismissed suggestions that Switzerland would regard themselves as clear favourites despite FIFA's rankings gap.
"Everyone has the right to their own opinion and show their confidence," Barbarez said.
"When we were playing against Italy in the play-offs, we had a similar sort of sentiment publicly, but we stayed focused on ourselves."
Thursday's fixtures mark the beginning of the second round of group-stage matches.
On Wednesday, England produced one of the tournament's most entertaining matches, defeating Croatia 4-2 in Group L. Captain Harry Kane scored twice, while Jude Bellingham also found the net.
Portugal, however, were held to a surprise 1-1 draw by the Democratic Republic of Congo.
The result renewed scrutiny of Portugal coach Roberto Martinez's continued backing of Cristiano Ronaldo, who is appearing in his sixth World Cup at the age of 41.
Ronaldo struggled to influence the match, recording only 25 touches, but Martinez defended his decision to keep the veteran forward on the pitch.
"It makes no sense to take off the best goal scorer in world football in a game that you need goals," Martinez said.
Ronaldo has now gone 10 consecutive major tournament matches without scoring, prompting criticism in the Portuguese media.
Sports daily A Bola wrote that Ronaldo appeared "crushed by the pressure" and had become "himself a problem", while Publico said the national team "remains hostage to its faith in Ronaldo".
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