Lionel Messi failed to emerge for the second half of Barcelona's 2-2 Champions League draw at Paris Saint-Germain after suffering a reported hamstring injury.
This per Barca's official website:
According to the Club’s Medical Services, Leo Messi picked up an injury to his right hamstring in the first half of the match against PSG. The player will undergo further tests on Wednesday to determine the extent of the injury
Without Messi on the field, Barca conceded twice and will now go back to Camp Nou for the second leg with PSG believing they can win.
They'll believe even more strongly if Messi is ruled out through injury.
In this clip, B/R lead writer Will Tidey looks at the potential impact of Messi's injury on the tie.