Chelsea 'have to improve' admits Fernando Torres Fernando Torres warned Chelsea could not keep relying on luck to stay in the Champions League after another dose of outrageous fortune helped get their title defence back on track. Last night's last-gasp 3-2 win over Shakhtar Donetsk proved providence was still smiling on the Blues after last season's astonishing triumph as they survived a Stamford Bridge onslaught to snatch a vital three points. Defeat was rough justice for a Shakhtar side that dominated much of a thrilling game and arguably deserved to complete a home-and-away double over the holders. The Ukrainian champions, who had not lost in almost a year prior to last night, were badly let down by their goalkeeper, who gifted Torres the opening goal when the striker charged down his clearance and was also lobbed by Oscar after racing off his line to head away a harmless cross. Torres admitted Chelsea could not keep relying on such lucky breaks if they were to hold onto their place in the top two in Group E after their upcoming trip to Juventus. He said: "I'm happy with the result but we know we must do much better. We know we have to improve. We have been creating problems for them, pressing and creating chances from their mistakes, but not when we have the ball like we're used to. This kind of situation cannot happen again because, especially in the Champions League, at times like these you can be out. Torres insisted he would rather Chelsea were lucky than unlucky and hailed the never-say-die spirit which played just as big a part in last season's Champions League triumph and was in evidence again last night. "When we needed to win, we did," he added. We did it against Valencia, Napoli and Barcelona - also the final against Bayern Munich. This was really the first big test of the season and we did it as well. We were a bit lucky - I think maybe the draw was the more fair result - but Chelsea has this special thing that no-one can buy. That's good. We have to keep the good luck on our side. Defender Gary Cahill admitted Chelsea had been under siege last night. "At times, there were four, five players up front," he said. They've got a lot of pace in the team as well, so I'm glad we don't play against them every week because they really impressed me. It makes the win even sweeter in the last minute of the game. It's a massive three points for us. He added: "We knew leading into the game how big three points would be. The manager stressed that to us. We keep pushing and pushing and pushing. We never know when we're beaten. Looking ahead to the penultimate Group E game in Turin, in which victory would seal Chelsea's qualification, Cahill said: "It's important we keep our foot on the pedal."