The Barcelona forward found the net midway through the second half of Argentina's World Cup opener with Bosnia-Herzegovina, doubling his side's lead at the Maracana with a fine solo effort.
Bosnia did pull one back through Vedad Ibisevic, but Argentina held on to take a 2-1 win.
Messi had cut a frustrated figure in the first half, and the relief was there for all to see after he lit up Brazil's most famous stadium with the kind of goal that he has become famous for at Barca.
Midfielder Gago had been brought on at half-time in place of Hugo Campagnaro, and Messi feels that change was pivotal to his improved showing in the second half.
"In the first half I was not able to play as I wanted. Things did not go my way," Messi said.
"With Gago there is an understanding. When he came on, I moved a few metres ahead."
Despite opening the scoring early through a Sead Kolasinac own goal, Argentina were stifled for long periods by a well-organised Bosnia side, who were making their debut on the World Cup stage.
And Messi is anticipating a similar struggle against Iran in Belo Horizonte on Saturday.
"The important thing (against Bosnia) was to win," he said. "Both our remaining games will help us to improve.
"The next game will be similar. Our rivals are going to defend."
