Rafael Benitez has defended Liverpool's zonal marking system and vowed to continue with it in Tuesday's Champions League clash at Chelesea.The clubs meet again at Stamford Bridge in a quarter-final second leg, with Chelsea seemingly in an unassailable position with a 3-1 lead.In the first match Liverpool conceded two goals from corners when Branislav Ivanovic produced a pair of towering headers, as the Anfield men's defensive play at set-pieces fell apart.Benitez said: "We feel we can handle Chelsea in the air. There was a lot of talk last week about our zonal marking system but all the top clubs have conceded about the same from set-pieces this season, it is not just the system that matters."And we scored a fine goal from a set-piece on Saturday against Blackburn, and they use man marking. Then I watched Aston Villa play Everton on Sunday and there were six goals and both sides use man marking."We are happy with the way we defend, it is all about the quality of players in the end. Zonal marking has been good for us in the past, and it will be good for the future."It depends on the type of player you have. We have used it for five years here and we have not conceded any more than anyone else from set-pieces."Benitez also refused to react to comments from the Danish referee for the first leg, Claus Bo Larsen, who implied that Chelsea had tried to influence his handling of their three players on yellow cards.Larsen did book Chelsea skipper John Terry - who is out of this game now, and complained that some Liverpool players were trying to get him cautioned after a clash with goalkeeper Jose Reina.But all Benitez would say was: "I felt the referee did a very good job in the first match."And the booking (for Terry) was very obvious and the correct decision."Liverpool expect to have skipper Steven Gerrard back in the side, having been rested for Saturday's win over Blackburn with a groin injury.Benitez said: "Steven is important, a key player for us. He has power and he can score goals, we can win without him but it is easier if he plays."We have already won at Stamford Bridge this season. We ended their long unbeaten home record and that is a massive boost to our confidence."We can do it if we work together and we score in the first half. If we do not do that it becomes increasingly more difficult, mentally."If we score a second goal then they will be under real pressure. But we know we must be almost perfect."And we know that with Steven and Fernando (Torres) together on the pitch we do have a good chance."People have written us off. Maybe we have nothing to lose, which means we can be positive, relax and hopefully then not make mistakes."Liverpool, who will be playing their 300th European match, will also have midfielder Javier Mascherano back for the game, having been suspended from the first leg.But the Anfield men have a mountain to climb and have won only twice at Stamford Bridge in 25 games over 20 years.And only twice in 75 visits to the ground have Liverpool achieved the sort of result needed to win this tie.Benitez must also decide whether to retain Daniel Agger in central defence, after his goal-scoring performance against Blackburn on Saturday, ahead of Martin Skrtel.