Mexico extended their record number of CONCACAF Gold Cup wins as Jonathan dos Santos' strike gave them a narrow victory over the United States.
LA Galaxy midfielder Dos Santos latched on to a smart Raul Jimenez back heel to fire in off the bar in front of 62,493 fans at Chicago's Soldier Field.
Christian Pulisic had a good early chance but US boss Gregg Berhalter said Mexico were the "better team".
The Gold Cup, referred to as the Concacaf Championship before 1991, crowns the continental champions of North America, Central America and the Caribbean.
Mexico now have 11 wins in the tournament's history, five more than the US, who claimed the biennial tournament in 2017.
Moments after new Chelsea signing Pulisic was denied in a frenetic opening, US striker Jozy Altidore fired wide when one-on-one with the goalkeeper.
Guardado headed a Jordan Morris effort off the line after half-time before Dos Santos produced the game's decisive moment with a clinical left-foot finish.
The goal delivered Mexico their eighth success since the tournament was re-branded in 1991.
Wolves striker Jimenez finished as the tournament's joint-second leading scorer on five goals alongside Canada striker Lucas Cavallini - with the 28-year-old's team-mate Jonathan David on six.