RAFA BENITEZ has launched a passionate defence of his preference for zonal marking and insisted individual errors are to blame for Liverpool's poor defensive record.[LNB]The Reds conceded two more sloppy goals as they were held to a 2-2 draw by Manchester City on Saturday lunchtime, the worst being Emmanuel Adebayor's unmarked header from Craig Bellamy's corner.[LNB]That was the eighth time since the opening day of the season Benitez has seen his back four breached at a set piece, a figure which accounts for 40 per cent of the 20 goals they have conceded so far.[LNB]It is proving hugely frustrating for Benitez, whse side have only won once in the Premier League since thrashing Hull City 6-1 on September 26, and explains the reason they find themselves in seventh place.[LNB]However, the manager is adamant the situation will turn around once injuries clear and he is able to play his preferred back four for a significant amount of time.[LNB]'When you're using a zonal marking system you have to attack the ball and if there's a player near you, you have to challenge,' he said.[LNB]'We watched some set pieces beforehand and Richard Dunne scored against them when they used man to man. In England 35 per cent of the goals come from set pieces.[LNB]'It is clear you have to attack the space or the player, it doesn't mean you stand like a post.[LNB]'The majority of players believe in it, maybe you can find one or two who don't.[LNB]'But we were one of the best - THE best - before. This year has been bad but it is still early in the season.[LNB]'We will see how things are at the end.'