Brazil were undone by a slice of magical talent on Wednesday as they fell 2-0 to Mexico in their first competitive match under coach Dunga.
Nery Castillo set Mexico on their way with a goal any Brazilian player would have been proud of before Ramon Morales curled in a 30-metre free kick.
Chile twice came from behind and then scored a late winner to beat Ecuador 3-2 as drama dominated day two of Copa America.
The competition had begun with Peru stunning Uruguay 3-0 and Bolivia twice coming from behind to hold hosts Venezuela 2-2 on Tuesday.
But Wednesday's Group B double bill in Puerto Ordaz was even more gripping as the action overshadowed the logistical problems at the tournament, where several venues are still not completely finished.
Mexico had arrived under the shadow of Sunday's 2-1 defeat by the United States in the CONCACAF Gold Cup final, without several key players and amid reports of rifts in the squad.
Defending champions Brazil, on the other hand, were raring to go and bury the memories of last year's lacklustre display at the World Cup.
They had played only friendlies since Dunga took over in August, losing once in nine outings.
But against all odds, Mexico went ahead in the 21st minute with a sublime piece of skill by Castillo, who chose to play for Mexico this year after also being chased by Uruguay and Greece.
SECOND WIN
Latching onto Juan Carlos Cacho's chip into the area, the Olympiakos striker flicked the ball over Juan and then past goalkeeper Doni without letting it touch the ground in the 21st minute.
Morales free kick eight minutes later gave Mexico their second successive win over Brazil following their 1-0 victory at the Confederations Cup two years ago.
Brazil took control of the game in the second half but were foiled by goalkeeper Guillermo Ochoa, the crossbar and defender Fausto Pinto, who cleared one chance off the line.
With the last move of the game, Castillo broke away, ran half the length of the pitch, rounded Doni and then shot wide of the open goal.
"We lost concentration and conceded the goals," said Dunga. "We recovered and showed our quality but the ball would not go in."
The game was preceded by a five-goal thriller in which Luis Antonio Valencia and Cristian Benitez twice put Ecuador in front, only for Humberto Suazo to equalise each time.
Ecuador were twice denied by Claudio Bravo while leading 2-1 and paid heavily when substitute Carlos Villanueva curled in an 87th minute free kick.
"We're a good team that sometimes plays well," said Chile coach Nelson Acosta. "Today, we didn't have a good game but we muddled through."
Ecuador coach Luis Fernando Suarez said: "It was one of those games where the opponents don't beat you but you lose the game yourselves."
The tournament continues on Thursday with a Group C double bill in Maracaibo. Paraguay face Colombia in the opening match, then favourites Argentina meet the United States.
