at his best

at first

At first it seemed Rosetti favored Liverpool a little bit. For instance he whistled for a tiny minor foul by a Chelsea player when Liverpool defender Skrtel was carried off the field. Very convenient for Liverpool when Chelsea saw their prey hurt. But no, this is not Rosetti. Maybe Rosetti felt pity or didn't want the match to be influenced by it. Or maybe he really saw a foul.

asistants

Having overruled one assistant about a throw-in (and rightly so) he believed the other one immediately flagging for off-side when Essien scored. At least one Chelsea player blocked the goalie's view. Bad luck for Chelsea, but a minute or so later they got to take a penalty when Hyypia fouled. Nobody protested, Rosetti was right.
Rosetti is a man to notice details. Often he whistled for a foul only visible in repeat. And repeating the situation you can see that Rosetti always stands in the right place.

match

Two great shots by Drogba from difficult angles, a penalty, a great goal by Torres and a lucky shot by Babel. "What the hell", Babel must have thought, "I'll try a shot, at least I don't have to run all the way to the goal again for nothing".