There was always a danger that after last Tuesday's thriller at Stamford Bridge, the second leg of Wednesday's quarter-finals would prove anti-climactic. As it turned out, they were anything but. Cristiano Ronaldo's wonder goal against FC Porto had pundits puzzling over their superlatives once again, and Arsenal FC's terrific performance against Villarreal CF laid down a marker that Manchester United FC will do well to match in the semi-finals.

Ronaldo strike
Ronaldo has been slow to hit the heights of last season when he top scored in the competition with eight goals, but when it mattered most he produced a performance and goal to leave his manager Sir Alex Ferguson purring. After being the dominant figure en route to the title in Moscow, Ronaldo has seen his lustre stolen this term by Lionel Messi who is tipped to take his European Player of the Year crown too. Ronaldo's warning shot in Porto suggests that battle is not over yet. Whether one of those two mercurial talents will have the final say in Rome on 27 May is a compelling subplot to a memorable UEFA Champions League season that promises more fireworks to come with four attack-minded teams through to the semi-finals.

'The way football should be played'
Arsenal FC have put their mid-season slump well and truly behind them and are playing with the belief and confidence that carried them through to the final in 2006. The team may have changed but Arsène Wenger's attacking philosophy is just the same and will make their meeting with United one to savour. "We are two good footballing sides, so it should be a terrific semi-final," his opposite number Sir Alex said. "Our game earlier in the season [a 2-1 Arsenal win] was fantastic. It was the way football should be played and we will look forward to it."

'We like to attack'
FC Barcelona coach Josep Guardiola approaches every game in that same spirit. "What we want is to play well and for our football to generate respect," he said. "We like to attack teams and to create the most amount of goal opportunities we possibly can." With Messi – the competition's top scorer this season with eight goals – Samuel Eto'o and Thierry Henry to the fore they have been doing just that. Barcelona lead the competition with 29 goals so far, are the only side still in it to have scored in every match, and have hit four or more in four of their ten games, including against both the French and German champions in the knockout stage.

Positive
Under Guus Hiddink, their semi-finals opponents Chelsea FC are also direct and positive. In the quarter-finals Hiddink's Chelsea scored two more goals than the Blues had managed in their eight previous UEFA Champions League matches against Liverpool combined. "We know we can score goals," Hiddink said. "Whenever we can we try to take the initiative." That positivity seems to sum up the UEFA Champions League over the past two seasons. For the second season in a row three English sides are through to the semi-finals, but their direct, positive and attacking approach has kept all of Europe enthralled. In 2006/07 309 goals were scored in 125 matches at an average of 2.47 goals a game. Last season 330 goals were scored at an average of 2.64 goals, while this season 320 goals have been scored at a similar average of 2.66 goals per game. With four teams intent on attack in the semi-finals, there should be plenty more goals and excitement yet.