1 Torres is their chief tormentor

Believe it or not, the shadow of his former self wearing the Chelsea No9 shirt has the best record of any striker in recent history against Barcelona. He's scored seven in 10 games against them. And although the last of those goals was scored in September 2005 (Leo Messi was 17, Saddam Hussein was still knocking about, Liverpool were European champions – it was a while ago), it may be that the mere sight of a Barça jersey reminds him what it is he used to do best: score goals. Then again, Roberto Di Matteo may start with Didier Drogba instead.

2 Messi has not scored against them

Barça's little genius (well, this one anyway) has scored almost a goal a game in his career to date, but in six matches against Chelsea he has not hit the net once and Barça have not beaten Chelsea in the past five. It's true that the Chelsea teams he's faced previously were better than this lot, but the lineups weren't all that different either, and John Terry and co have managed to keep him at bay so far. So, perhaps at the back of his mind, there lurks the tiniest seed of doubt when he plays against them. Although, the eye-boggling 63 goals he has scored so far this season suggest that Chelsea's defence may have to dig in deep to unearth it.

3 Barcelona have been beaten this season

And by teams that even Chelsea would fancy their chances against. Both were away defeats, the first was a 1-0 loss at Getafe in which Barça failed to score despite having 20 attempts on target and 73% possession. The second, February's 3-2 defeat at Osasuna, featured a Barça team missing two parts of their holy trinity of Messi, Xavi and Andrés Iniesta, amen. So perhaps it's a realistic aim for Chelsea to nick a win by a one-goal margin at Stamford Bridge. At Camp Nou, however, Getafe were thrashed 4-0, while Osasuna were sent limping home in a daze on the back of an 8-0 mauling. Ouch.

4 Chelsea haven't lost in seven matches

OK, so they haven't played anyone close to Barça's quality either but by hook or by crook they have started to grind out results in a way that they weren't capable of earlier in the season. Roberto Di Matteo's presence – whether the senior players listen to him or not – has been the catalyst for a strong collective mentality returning to the squad and, when they have conceded goals, instead of rolling their worst woe-is-me eyes in resignation, they've rolled up their sleeves and gone for the jugular, as they did in the thrilling finish to their 4-2 win at Villa Park.

5 Get lucky

If all else fails Chelsea can hope the planets align in such a way that they interfere with Felix Brych's judgment and the German referee drops the kind of a clanger Martin Atkinson did at Wembley on Sunday and awards them another ghost goal. They may feel the football gods owe them one after Tom Henning Ovrebro's stoic approach to waving away a raft of solid penalty claims in the 1-1 semi-final away-goal defeat to Barça in 2009. Then again, maybe a wrathful rain will bring a flood of goals, but instead of the ghost being credited with them, it will be Messi instead. Start praying.