Lionel Messi's second-half goal gave Argentina a 1-0 home win over Ecuador on Thursday to get their 2026 World Cup qualifying campaign off on the right foot.
World champions Argentina were dominant in possession but frustrated in attack as they struggled to make the breakthrough.
Captain Messi, however, continued the fine form he is showing with club side Inter Miami by scoring from a free kick after 77 minutes.
"We played against a great team, with good players and physically strong," Messi told reporters.
"Everyone always wants to beat Argentina and even more so now that we are the world champions. We can't relax, we have to improve on what we've been doing.
"The objective is to qualify for the World Cup again. We really enjoyed what we did but we have to look ahead."
Messi's goal also tied him with close friend Luis Suarez of Uruguay as the all-time top scorer in the South American qualifying competition with 29.
"It's a pleasure for me that we are both there," said Messi, who has now scored 104 international goals. "Given what the qualifiers mean for us in South American football, it's a very nice thing for both of us."
Argentina will next play at Bolivia on Tuesday.
In other qualifiers, Paraguay drew 0-0 with Peru while Colombia claimed a 1-0 home win over Venezuela.
The first round of CONMEBOL qualifiers continues on Friday when Uruguay host Chile before Brazil take on Bolivia.