Messi suffers calf injury on return to Barcelona training

Lionel Messi is set to miss Barcelona's upcoming trip to the USA after suffering a calf injury during his first training session back at the club.

Having been given extended leave following Argentina's run to the semi-finals at this summer's Copa America, Messi only returned to the fold on Monday.

However, he was forced to pull out of the session with what doctors have diagnosed as a grade one calf strain.