Under pressure from Dirk Kuyt, Benfica goalkeeper Julio Cesar could only flap a Gerrard free-kick into the path of Torres, who rolled the ball into the unguarded net. But the Spaniard’s celebrations were cut short by a flag, television replays suggesting Kuyt’s elbow was in an offside position.

Benfica had already been the dominant attacking force before Babel’s dismissal only tightened their grip on territorial possession.

With Carlos Martins probing in central midfield and winger Angel Di Maria intent on further enforcing his burgeoning reputation, Liverpool’s defence were continually pressed back.

Most of the chances came to Cardozo. The first came after just 12 minutes as the Portuguese sought an immediate equaliser, the striker firing over at the far post from an excellent Martins cross.

Cardozo was then twice wayward with headers while Pablo Aimar, formerly at Valencia with Benitez, couldn’t control a Martins throughball that had been unwisely left by Agger.

Di Maria was next to try. Narrowly over with a 20-yard effort and wide with another shot from range, the Argentine’s drive was hounded out by the Liverpool defence in first-half injury time after Pepe Reina’s punch landed at his feet.

And it was all Benfica after the break, Torres forced to scavenge for himself up front with Liverpool given no option but to strike on the counter-attack.

There were ambitious pleas for a penalty when Aimar went to ground while tracked by Javier Mascherano, while Cardozo wasted another chance when sending a free header over from Di Maria’s right-wing free-kick.

But the Benfica man finally got his goal on the hour, although again there was a hint of controversy that favoured the home side.

Agger was adjudged to have fouled 20 yards from goal despite appearing to be grappled to the ground. Cardozo slammed a free-kick against the inside of Reina’s right-hand post and, during the scramble that followed, Insua stupidly upended Aimar and Cardozo scored from the spot.

On a rare breakaway, Torres wasted a golden chance to regain the lead 14 minutes from time when, after being sent clear following a one-two with Kuyt, the Spaniard pulled his shot horribly wide.

And that miss became costly on 79 minutes when a sliding Carragher was harshly deemed to have handled Di Maria’s cross by referee Eriksson and Cardozo placed the penalty in the same spot.

What else? The promise of a truly explosive second leg in six days’ time.