I don't think it's anything serious, I wouldn't read too much into it, he could use a rest though.
If he goes out for anything longer than 6 weeks the season is over for us despite the lead we've built at the top.
Twitter is place for doom mongers...
Who scored means nothing.
Seen some pics on twitter where he is seen touching his hamstring. Think he has discomfort...should be rested against Olympiacos.
Rest him, to be sure that nothing is goes wrong. The game tonight can be won without him, and isn't definitive anyway.
Messi is mature enough to know the risks of playing injured and the complications that might follow.
Can small tissue tears be detected by today's medical equipment? Any doctors here perhaps?