Secrets behind the Champions League goal rush

Conventional wisdom has it that as the stakes get higher football matches become cagier. Two-leg fixtures are also supposed to breed caution. So try and explain the goal rush of the Champions League's knock-out stages. Last season, in what Andy Roxburgh, Uefa's technical director, termed "a lean and hungry" knock-out phase, there were 62 goals in 29 matches (2.14 per game). This season, after 20 knock-out matches, there have been 59 goals (2.95 per game), 14 in the four quarter-final first-leg fixtures this week (3.5 per game). The Champions League average over its 16 seasons, including group stage ties, is 2.62.

One reason is the importance of the away goal. Few ties have actually been settled on away goals, just 16 in as many seasons, but, noted Uefa's Technical Report on last season's competition, "it can influence the play and it can be psychologically decisive". Away teams are often more adventurous, an approach exemplified by Porto at Old Trafford and Chelsea at Anfield. They are also inclined to attack as experience suggests in many cases it is the best form of defence. Sitting back at either of those grounds and allowing Liverpool and Manchester United waves of attacks is asking for trouble.

Another key element this week was the rush of early goals. In all four matches a goal was scored within 10 minutes. Such goals have the effect of releasing tension, in both sides. That can lead to chances on the counter-attack as one team feels the need to push forward – as shown by Chelsea's third goal on Wednesday.

The surprising aspect of this week's ties was how few late goals were scored, just two at Old Trafford. Last season nearly a quarter of Champions League goals were scored after the 75th minute, including five per cent in added time. "The last 10 to 15 minutes is a key period from a coaching perspective," said Arsène Wenger. Maybe at that stage this week the players, like the fans, were simply drained by the preceding drama.