The new Barça skipper was eliminated from the World Cup at the Last 16 stage after a disappointing tournament from Argentina that had even threatened to erupt in mutiny against coach Jorge Sampaoli during a challenging group stage.
He has had a month off since La Albiceleste were knocked out by eventual champions France and, according to Mundo Deportivo, Messi's first talk of pre-season will be to be participate in the usual mandatory medical tests to gauge his current fitness.
The five-time Ballon d'Or winner will not be the only returning Barça player reporting for duty this week, with Spain World Cup trio Gerard Pique, Sergio Busquets and Jordi Alba also to return.
It follows the recent arrival in Dallas of goalkeeper Marc-Andre ter Stegen, who was knocked out of the World Cup early with Germany, while Colombian defender Yerry Mina is also expected to start training soon. That is, unless he isn't sold to any one of numerous rumoured suitors.
Luis Suarez was knocked out of the World Cup at the quarter final stage and is expected to arrive a few days after Messi, Pique, Busquets, Alba and Mina.
Whether the Uruguayan will make it to the United States or simply wait in Catalunya remains to be seen as the squad are playing their third and final American friendly on 4th August.
Barça are due to face Sevilla in the Spanish Super Cup on 12th August, before Argentine giants Boca Junior visit Camp Nou for the annual Joan Gamper Trophy three days later.