Kept out for 90 minutes by Iran's stubborn defense, Messi finally struck in injury time Saturday with a curling, left-foot shot that gave Argentina its second far-from-convincing win in Brazil, beating Iran 1-0 after edging Bosnia 2-1 in Group F.
Argentina coach Alejandro Sabella conceded that Iran gave his team a tough time in the second half, "But having Messi resolved everything."
So far, the Barcelona wizard is the only Argentine player to score in Brazil and he is as vital to his stuttering team as previous No. 10 Diego Maradona was when he scored five and created five more of Argentina's 14 goals as the country lifted the World Cup in 1986.
Maradona was watching in Belo Horizonte as Argentina struggled to break down Iran and goalkeeper Sergio Romero kept his team in the match with a finger-tip save from Fulham forward Ashkan Dejagah's second-half header.
Later Saturday, Germany was playing Ghana in Group G and and Nigeria was taking on Bosnia in the other Group F matchup.
Messi appeared to have won a battle with his coach over which formation to use as Argentina started with three forwards in a 4-3-3 system. He was critical of Sabella's decision to start the match against Bosnia with a more defensive 5-3-2 formation. Sead Kolasinac scored an own goal and Messi got the second for his team in that match.
Inevitably, it was Messi who stepped up in the dying seconds to steal the points against Iran.
Before the match, dozens of Jewish demonstrators held a minute's silence, demanding justice for a still unsolved bombing attack against a Buenos Aires Jewish center 20 years ago that left 85 dead and for which Iran has been blamed.
In Rio, England players struggled to digest their early World Cup exit as they trained for their last match in Brazil and Wayne Rooney backed embattled coach Roy Hodgson.
"Roy is the man to take us forward," Rooney said.