This week, we see just why the precious away goal is hated

Like it or loathe it, this is the moment when the away goals rule comes into play in the Champions League. It could play an important role in determining which sides go through to the quarter-finals, both this week and next.

Not that many ties are decided on away goals. There was one spectacular example last season, when Roma came back against the odds and knocked out Barcelona after losing the first leg 4-1, but that is a rarity. It is more that the rule can condition the way managers prepare their game-plans, and also affect the psychology of players once a game is under way.