Barcelona put one foot and four toes into the quarter-finals of the Champions League with a 2-0 victory over Manchester City at the Etihad Stadium as the hosts shot themselves in the foot.
A red card for Martin Demichelis for bringing down Lionel Messi nine minutes into the second half tilted what had been an even clash firmly in the Catalans' favour, with Messi picking himself up to score his first-ever goal on an English club ground from the spot.
Prior to that, Barca had had lots of possession but were kept at arm's length by their hosts, who came close through a goalmouth scramble and Alvaro Negredo.
David Silva almost grabbed a late equaliser for them, but the tie was arguably put to bed when Barca's Dani Alves strode through a tired home defence to finish what could be a killer second away goal.
Here are six lessons learned from a night on which City were taught a harsh lesson about life at the summit of European football: