Puyol out of starting line up tonight with a sore knee apparently, Mascherano to step in for BCN.— AS English (@English_AS) March 12, 2013
With Puyol out, it appears Jordi Roura will likely go with Javier Mascherano in the central defense next to Gerard Piqué. It's not the worst thing ever for Barcelona since Mascherano is a capable replacement, but it's still a blow. Puyol is a leader on the pitch and a bit of a talisman for the club, if you believe in that kind of thing.
The potential upside is that Puyol didn't play well at all against Milan in the first leg so perhaps Mascherano will be able to better handle the speedy attack that Milan will undoubtedly thrown at the Barca defense.
Now back to your regularly scheduled programming.