*Chelsea failed to break down Aston Villa to leave the champions six points behind leaders Manchester United.* The visitors dominated the first half and should have been well ahead by the interval, but both Didier Drogba and Ashley Cole missed gilt-edged chances. Drogba miscued with a volley, while Cole headed straight at Gabor Kiraly. Outclassed in that opening period, Villa provided a sterner test for Chelsea after the break and Liam Ridgewell went close with a header. Chelsea had drawn their previous two league games, allowing leaders Manchester United to move seven points clear ahead of Tuesday’s game with Villa. And this was another stuttering performance as Chelsea struggled to replicate the high standards they have set themselves over the previous two seasons. In the absence of John Terry, Chelsea’s defensive problems have been well documented and the visitors suffered another blow in that department when Khalid Boulahrouz limped off with a knee injury in the opening half. But it was Chelsea’s attack rather their defence that let them down in an opening half that saw the visitors fail to convert a host of chances from the surfeit of possession they enjoyed. In scoring 13 league goals this season Drogba has probably been Chelsea’s most effective player, but even the Ivory Coast forward seemed to be affected by the Blues’ mid-winter malaise. Drogba should have put Chelsea ahead inside the opening 10 minutes, but his volley went into the ground and over the bar after Michael Essien crossed from the right. That flank proved a productive avenue for the visitors with Drogba soon swinging over a cross for Salomon Kalou, who was unable to get a clean header on the ball due to the diligence of Olof Mellberg. Essien was soon marauding his way down the right wing again, but when the cross came over Drogba uncharacteristically miskicked. Cole was the next Chelsea player to miss, sending his header directly at Kiraly. Just before the first half ended, Frank Lampard’s surging run brought him to the edge of the Villa box, but he failed to spot Claude Makelele, who was free on the right, and the attack broke down. Midway through the second half Andriy Shevchenko came on for Shaun Wright-Phillips as Chelsea manager Jose Mourinho opted to provide extra support for Drogba. But the Ukraine striker proved as peripheral a figure as he has for most of this season and he rarely touched the ball. Villa had barely an attack worthy of mention in the first-half, but as the game wore on the home side began to threaten from set-pieces and Ridgewell went close with a header from a corner. In the closing stages Chelsea launched one final onslaught, but Lampard put the ball over the bar from close range, while Drogba headed over. *Aston Villa manager Martin O’Neill:* “I thought we played with a ferocious amount of determination, which we had to against a side like Chelsea. “We had to try to match them as much as we possibly could and I have nothing but praise for the players. “They worked tirelessly and stuck it right to the end. We have played better and lost games.”