FC Barcelona ✔@FCBarcelona "Tests confirm that Leo Messi has a bruised bone on the outside of his left knee." #FCBLive
These things are minor, but sometimes end up a long pain in the ass. I had a bruised bone once that prevented me from playing for 7-8 months.
However, most likely Messi's is very small and he can be expected to return to the line up already this year.
Another source, not so reliable, claimed Messi could play on Sunday already, but this has not been confirmed by any other party.