Benitez must have had just as much fun watching Mohamed Sissoko and Steven Gerrard neutralise Claude Makelele and Frank Lampard. Chelsea will have to take consolation from the league and from taking part in one of the most exciting and fiercely contested semi-finals for years.
At one point running away with the game, Liverpool spent the last quarter defending desperately and were almost undone at the death when Joe Cole missed a wonderful chance to send the game into extra time.
No one could have grumbled about that, though Liverpool were just about worth their win, both for their doughty defending at the end and the way they made light of Chelsea's so-called invincibility for a good hour of the game.
The gulf in resources might be unbridgeable in the league, but Liverpool have found the various cups a great leveller. This was the tenth meeting between these clubs in two seasons, so it is fair to say they know each other pretty well. Liverpool went into the game with only one win from the series and that by a single, disputed goal, yet still they could only find room for Djibril Cisse and Fernando Morientes on the bench, with Peter Crouch and Luis Garcia in attack.
Chelsea had the ostensibly more dangerous Hernan Crespo and Didier Drogba in partnership up front, but had evidently decided width was unimportant. The wing positions were notionally occupied by Paulo Ferreira and Frank Lampard, with Arjen Robben, Joe Cole and Damien Duff kept in reserve until Liverpool stunned them by taking a two-goal lead.
Chelsea's early chances fell to Drogba and were missed. He put a stooping header wide when a Lampard corner was flicked on at the near post and was guilty of an even more wayward finish when the flag stayed down and Lampard's through ball left him one-on-one with Jose Reina.
Liverpool responded by taking the lead with almost casual ease. Xabi Alonso had just given Liverpool encouragement with a speculative shot that Carlo Cudicini saw late and only just punched away, when John Terry was harshly adjudged to have fouled Luis Garcia just outside the penalty area. Gerrard and Riise stood over the free-kick and fooled Chelsea into expecting a blast, whereas the pair calmly played the ball to each other before Riise passed it through the wall and beyond Cudicini.
With 24 minutes of the first half remaining the ground waited for the Chelsea response and was still waiting when the interval arrived. Only a long shot from Lampard vaguely troubled Reina, whereas Gerrard produced a top class cut-back for Luis Garcia, only to see his team-mate snap at the chance. Chelsea brought Robben on for the second half, moving Ferreira back to left-back, and there soon arrived the first sign that it might not be their day when Terry rose at the other end to head in from Robben's free-kick, only to turn and see Graham Poll shaking his head. Replays suggested the referee had been right in ruling Terry had climbed on Riise.
Luis Garcia then missed another open goal off Gerrard, this one even more open than the first, before redeeming himself gloriously in the 53rd minute. William Gallas made a hash of dealing with a throw on halfway, the ball glancing off his head and bouncing behind him, where Luis Garcia was on to it in a flash. The striker still had 40 yards to goal, but anyone who saw Liverpool beating Juventus last season knew what would happen next. Luis Garcia knocked the ball forward, chased it and just as the cover was closing in he shot early and accurately, looping the ball unstoppably over the stranded Cudicini.
Jose Mourinho sent on two more substitutes with almost half an hour left, though Robben proved the most impressive. A slaloming run into the area brought a shot that Reina was grateful to hold.
Unfortunately for Liverpool, Riise misjudged a clearing header, sending the ball high across his own goal, and, with the advantage of a start, Drogba reached it before Reina to head into an empty net.
The last 15 minutes were as frantic as any FA Cup romantic could wish. Liverpool found themselves penned back, Chelsea tried everything they knew but could not break them down, with Sami Hyypia and Jamie Carragher distinguishing themselves in the now familiar blockade.
Liverpool hearts stopped beating in the final seconds when Joe Cole took Robben's pass and spun to give himself a clear sight of goal, only to shoot wildly over.
Mourinho was not impressed. 'You have to take those sort of chances in a game like this and we missed one in each half,' he said. 'It means we miss out on a big match and that hurts.'
Man of the match: Luis Garcia
Missed a couple of sitters but, as against Juventus the Champions League last season, scored a screamer and generally caused the Chelsea defence problems with his close control and darting runs. Would be the first to thank Sissoko, Gerrard and Alonso for providing the platform.