Lionel Messi expects to be out of action for "a little while" after suffering a calf injury during Barcelona training on Monday.

The Argentina star sustained a grade one strain to his right calf muscle in his first session back with LaLiga's champions after his post-Copa America holiday.

The 32-year-old will miss Barca's pre-season trip to the United States while he recovers from the problem.

Although Barca have not put a timeframe on his recovery, Messi does not seem to think the injury will keep him sidelined for long.

"I was looking forward to starting and unfortunately I had an accident in the first training session that will leave me out for a little while," he wrote on Instagram.

"I'm grateful for all your messages and displays of affection, I wanted to be with the team and with the people who follow us in the USA.

"It wasn't to be this time, but we'll see each other again soon. A hug to everyone."

Barca face Napoli in Miami and Ann Arbor this week in the final stretch of their pre-season duties.

They begin their league title defence away to Athletic Bilbao on August 16.