Messi scored his team’s fourth goal right before the break, having also set up Julián Álvarez to open the scoring in the 17th minute. Angel di Maria scored twice in between.
Argentina coach Lionel Scaloni made four changes at halftime but opted against resting his star player, leaving Messi on for the full 90 minutes.
Messi has now scored 10 goals in his last five appearances for Argentina and took his overall tally to 91 goals.
Inter Milan forward Joaquín Correa scored the visitors’ fifth goal on the hour mark.
Argentina start their World Cup tournament against Saudi Arabia on November 22. They also face Mexico and Poland in Group C.
“We’re confident,” midfielder Rodrigo De Paul said. “But for many it will their first World Cup so the first game will be very important.”
FULLKRUG RESCUES GERMANY
Niclas Fullkrug scored on his Germany debut as the four-time World Cup champions earned a 1-0 win over Oman in Muscat.
It was far from a convincing performance from Germany, which looked susceptible in defence and prone to mistakes.
But Fullkrug’s introduction for the second half brought a new dimension to an attack that had failed to spark in the first half.
Youssoufa Moukoko struck the post on his Germany debut right before the break, which as close as the visitors got in the first half.
The 17-year-old Moukoko was Germany’s youngest debutant since Uwe Seeler, who was younger by 16 days in 1954.
Moukoko then made way at the break for Füllkrug. The 29-year-old forward almost scored early in the second half only to be denied by a good save from the impressive Ibrahim Al-Mukhaini.
Germany remained vulnerable at the back but Oman substitute Muhsen Al-Ghassani somehow missed with the goal at his mercy in the 72nd.
The hosts were to rue the miss when Kai Havertz set up Füllkrug to score what proved the winner in the 80th.
Germany face Japan, Spain and Costa Rice in Group E.
LEWANDOWSKI LEFT OUT
Robert Lewandowski watched from the bench as Poland edged Chile 1-0 in a bruising encounter thanks to a late goal from Krzysztof Piatek in Warsaw.
Lewandowski didn’t play but will likely start Poland’s tournament-opening game against Mexico on Nov. 22.
Mexico lost their final warm-up game 2-1 to Sweden in Girona, Spain.
CROATIA BEAT SAUDI ARABIA
Andrej Kramaric’s late goal was enough for Croatia to beat Saudi Arabia 1-0 in Riyadh.
Croatia star Luka Modric played only the last 25 minutes, enough to set up Kramaric for the winner in the 82nd. Kramaric still had to elude five Saudi defenders before scoring his 20th international goal inside the far post.
Croatia coach Zlatko Dalic began with an unfamiliar lineup and gradually brought on his established players. Chelsea midfielder Mateo Kovacic, Hoffenheim forward Kramaric, Tottenham midfielder Ivan Perišic and Real Madrid’s Modric all came on in the second half.
Croatia are in Group F along with Belgium, Canada and Morocco.