Salomon Kalou earned Chelsea FC their first away win in this year's UEFA Champions League to leave the London club superbly placed to progress to the semi-finals.
Caution and defensive rigour reigned in a tight opening period that played into Chelsea's hands, and their calm at the back continued to serve them well as SL Benfica tried to open things up after the break. Having already hit the woodwork through Juan Mata, the English side then completed a fine night's work on the counterattack as Kalou slid in Fernando Torres's cross with 15 minutes remaining.
Benfica's desire to reach the last four for the first time since 1989/90 was obvious from the start, but the Blues did not take long to settle and were soon enjoying a comfortable spell of possession before unleashing the first attempt of the game. Former Benfica defender David Luiz strode forward and blasted beyond the far post.
More clear-cut openings were harder to come by, although Ramires – also back at his old ground – twice caused panic with bursts down the right as he looked to combine with Torres. Benfica's response then raised the decibel level among the home support, Óscar Cardozo chesting down Bruno César's lofted pass and volleying wide.
The Paraguay forward was able to get in behind the Chelsea defence on that occasion, but otherwise Roberto Di Matteo's men were quick to shut the gate to cut out through balls from Aimar and Co. The No7's next look at goal came via a left-wing Emerson cross, in fact, his header looping well over.
César did little better with a shot straight into Petr Čech's hands from distance as the visitors continued to keep things tight, and as half-time approached they began to venture forward again. Torres fired over after making room for himself and Raul Meireles sent Artur sprawling to his left to keep out a fierce attempt from 20 metres.
Having trailed 2-1 at the interval at SSC Napoli in the previous round, Chelsea could be satisfied with their first-half showing, though it took a goal-line block from Luiz to deny a thunderous Cardozo volley shortly after the restart. Benfica were clearly anxious to up the tempo, and César tested Čech at his near post, before Kalou headed Torres's cross off-target at the other end.
Cardozo joined the list of players unable to beat Čech from long range as the pace of the game accelerated, and – incredibly – the Chelsea No1 almost turned provider as his clearance evaded everyone before falling to Mata. The Spanish international rounded Artur only to shoot against the upright from a tight angle on the left.
The Eagles reacted with another spell of pressure, Axel Witsel's deflected shot dipping over and Čech parrying Jardel's header from a Nicolás Gaitán centre. They had not heeded the warning, though, and Ramires raced down the right to feed Torres, who promptly picked out Kalou to leave Benfica facing an uphill struggle at Stamford Bridge next Wednesday.