There are as many ways to enjoy a football match as there are people to enjoy them. One man's fascinating tactical battle is another man's turgid 0-0 draw; one woman's glorious carnival of attacking puissance is another's one-sided mismatch. It's up to you. But I think most people would agree that one of the more fascinating ingredients in any prospective game is when one or both teams are beset by insecurity.
Insecure teams don't play badly. They are not roundly outplayed, they are not thrashed. Instead, they play pretty well, but with a vague air of worry: they know, and you know they know, that it's all about to go horribly wrong. Often it doesn't. Sometimes it does.
So to Chelsea. The reason this season's Blues have been such fun to watch -- from a neutral point of view, that is; I'm sure their fans aren't particularly enjoying the conniptions -- is because they've played generally decent and occasionally excellent football in a profoundly insecure manner, and while the Premier League is flabby enough to absorb plenty such stumbles, Europe is an altogether more awkward place to stutter. Of the five continental games Chelsea have played they've had three good results (two wins and an away draw against Valencia) and two poor ones. And in both of the latter cases they had the game in their hands before it all went the way of the pear, like a man who falling victim to a violent sneeze just as the last card is placed onto the fragile, trembling pyramid.
The causes of this insecurity are obvious and well-trodden by now: a new coach with new ideas; a fractured, ageing and ill-balanced squad; a few senior players undergoing personal crises of form and focus; David Luiz*. But given all of that, the last thing Andre Villas-Boas and his neurotic nail-chewing squad will have wanted is a knock-out game against some seriously capable opponents.
* This was a joke! David Luiz is great and will be fine! At some point! Probably! He might do another goal soon!
For Unai Emery's men are in some tasty form. They've won seven of their last eight, scoring 22 in the process (and the odd game out was a quite ridiculous 3-2 defeat at the hands of 2011/12 Treble winners, Real Madrid). They top the informal but important Spain's Proper League Of Proper Clubs If We Ignore Those Two There, The Greedy Sods and, while you can read a more detailed tactical preview here, it's worth highlighting that they come fully equipped with every insecure team's nightmare: a damn fine striker. Roberto Soldado has scored 14 goals this season, just one fewer than Didier Drogba, Fernando Torres and Daniel Sturridge combined.
(With apologies to any Belgians reading, the next paragraph assumes that Bayer Leverkusen will beat Genk. Sorry. Kudos on the whole not-having-a-government thing though. Proper jealous.)
Add to that the oddity that the Champions League prefers head-to-head goal difference. If either side win, then they progress. A draw, however, will only benefit Chelsea if it's a blank; any kind of score-draw sends the Spaniards through. The last time Valencia failed to score? September. And while Chelsea are coming off the back of two consecutive clean sheets in the league, not even the most blue-tinted could describe the Newcastle shutout as anything less than fortunate.
Hovering over all of this: Roman Abramovich. It is generally assumed that the Champions League obsesses him, and this is borne out to a certain extent by his record of hiring and firing. Villas-Boas himself has acknowledged that while he believes that Abramovich is focused on the long-term three-year plan, a failure to get through the group stage might change that. Of course, firing Villas-Boas would be stupid, but then the point of being rich is to be able to do stupid things with impunity.
A little perspective? If you insist. Chelsea are favourites to win the game. They have yet to concede a goal at home in Europe this season (in two whole games), they have finally replaced John Obi Mikel (though defensive midfield doesn't feel right for a man named Romeu), Daniel Sturridge is scoring goals (and even playing well at times), and Juan Mata is a genius (despite looking as though he pilots a boat made from an acorn cup). And in any case, this is the crucial point: insecurity doesn't mean failure. It means the possibility of failure in a variety of interesting, exciting, and comical ways. What more could any reasonable neutral ask for?
The Champions League, as we know, is a bloated vehicle for the continued aggrandisement of the larger teams on the continent. As a result, games like this -- knockout games, basically -- for English teams have been precious rare before Christmas. So here's a bonus helping of crunch. Brows will furrow. Bums may even squeak. And if you need any further guarantee that it's going to be great, consider this: I, your humble previewer, will be missing the whole thing due to a poorly timed intrusion of real life. Bah. Enjoy it for me.