By the time Liverpool equalised on Sunday, Chelsea should have had the game won. They ought to have been at least two or three goals to the good, with Oscar, Juan Mata and John Obi Mikel all missing good chances. And the way Chelsea are defending at the moment, 1-0 never seems to be enough of a lead because they just cannot keep a clean sheet. Terry's injury is a worry. At the start of the season Roberto Di Matteo's team looked great going forward and secure at the back. There were four clean sheets in the first five league games -- but there have been none in the six since then. So what has changed? It is hard to escape the conclusion the absence of John Terry has been crucial. In the four domestic games for which he was suspended, Chelsea conceded a total of 10 goals. And some of the goals have been so basic. The two scored by Manchester United in the first few minutes of the league game at Stamford Bridge saw United carve through the left side of Chelsea's back line, where a lack of cover from midfield left Ashley Cole badly exposed. And the two goals Shakhtar Donetsk managed at the Bridge -- almost exact replicas of each other -- both saw Willian wander unmarked into the centre of the penalty area, free to stroke the ball home unchallenged. Against Liverpool, I thought Luis Suarez had been similarly unmarked as he headed home from