Argentinian Messi opened the scoring on 10 minutes after he had been brought down by Luca Antonini but Antonio Nocerino levelled just after the half hour after he was set up by Zlatan Ibrahimovic, making his return to the Nou Camp.
Messi restored the Catalans’ lead five minutes before the break as Alessandro Nesta was penalised for holding Sergio Busquets and inevitably the World Player of the Year was involved again for the third as his blocked effort rebounded for Iniesta to fire home for a 3-1 aggregate triumph.
Two first-half goals from Ivica Olic helped Bayern Munich to a routine win over Marseille that booked them a semi-final berth.
Already leading 2-0 from the first leg, the German side were always favourites to progress last night and so it proved as two clinical moments from the Croatian proved sufficient.
The result thus duplicated that of the first leg and took Bayern through 4-0 on aggregate.
Were it not for the heroics of visiting goalkeeper Steve Mandanda it could have been more and, while Bayern will now go on to a likely last-four meeting with Real Madrid, questions are starting to mount over the future of Marseille manager Didier Deschamps.
They are completely out of the domestic title race and were dumped out of the cup by unfancied opposition.