Lionel Messi was "tired" and taken off as a precaution, according to Inter Miami head coach Guillermo Hoyos, following his early exit from their 6-4 win over the Philadelphia Union.

The Herons staged a stunning comeback in the second-highest scoring MLS match in history, but it was overshadowed by Messi's substitution in the 73rd minute.

He signalled to the bench that he needed to come off after taking a free-kick and left the pitch holding the back of his left leg, to be replaced by Mateo Silvetti.

Argentina are yet to name their squad for the upcoming World Cup, but Messi is expected to headline it as they prepare for their title defence.

"As far as I know, we don't have a report on that yet, but he really was fatigued. It was fatigue," Hoyos said.

"Yes, it was fatigue. He was tired, the field was heavy, and rather than doubt, you always say not to take the risk."

Messi had registered two assists before having to go off, both for German Berterame, with Luis Suarez scoring a hat-trick before Rodrigo De Paul got Miami's sixth late on.

Milan Iloski had scored a hat-trick for the Union, but even with Bruno Damiana's goal, it was not enough to stop Miami.

The Herons head into the World Cup break second in the Eastern Conference, two points behind Nashville SC.

The Columbus Crew also rounded off the first part of the season with a win, beating Atlanta United 2-0 thanks to goals from Sekou Bangoura and Diego Rossi.

In the Western Conference, Los Angeles FC moved up to fifth after ending a four-game winless streak with a 1-0 victory over the Seattle Sounders, with Timothy Tillman netting a late winner.