Women's Champions League performance insights: Chelsea and Barça set pressing benchmarks

"Chelsea made it really difficult. They had so much intensity and, even with ten players, they really pushed us." The comment by Barcelona right-back Lucy Bronze summarised a fiercely contested UEFA Women's Champions League semi-final between two teams who set benchmarks in club football for high-intensity collective pressing and counterpressing.

After technical observer Jayne Ludlow analysed how Chelsea's defensive density earned a 1-0 first-leg win, Gemma Grainger commented on the pressing strategy that allowed Barcelona to overturn the deficit with a 2-0 victory in London, epitomised by the defensive contributions of midfielder Bonmatí which earned her UEFA's Player of the Match award.

UEFA's analysis unit has followed up their comments by taking a closer look at the way the two teams made life difficult for each other by pressing hard and high.

The pressing was relentless from the first whistle to the last. As the first graphic illustrates, the visitors came out of the blocks strongly, executing 30% of their pressing activities in Chelsea territory during the opening quarter-hour, whereas the home team pressed aggressively during the final 15 minutes of each half – especially when chasing the result with ten players in a hectic final segment in which Barça also upped their pressing intensity. Chelsea's purple patch of pressing at the end of the first period produced the regain in the final third which led to Sjoeke Nüsken creating a cutback opportunity for Lauren James.

However, in-depth analysis confirms that Barça were the more efficient team in terms of snapping into collective attempts to regain possession within seconds of losing it and disrupting the home team's build-up play – as illustrated by the second graphic. Both sides switched rapidly to pressing mode when their opponent had made two passes or less, but Jonatan Giráldez's players did so 44% more frequently than Chelsea.

The video in this section shows the home team's approach to a Barça goal kick: six players high and all ten outfielders in the opposition half. Immediate pressure on the goalkeeper provokes a long ball which is comfortably intercepted. Overall, however, Barça were more successful in obliging their opponents to play long. During the tie, Emma Hayes' side averaged 322 passes per game (by far their lowest tally of the season), of which 20.5% were long (by far their highest figure of the season).

The two teams set benchmarks for structured collective team pressing involving four or more players and/or the high-block pressing facilitated by Barça's compact attacking shape and balanced rest-defence set-up. At no point did Chelsea press individually – as shown by the graphic which also reveals the visitors' dominance in terms of immediate counterpressing by advanced players after ball losses in high areas.

The video starts with 19 of the 20 outfielders in a small area on the left of the Chelsea midfield. The fierce Barça press forces the ball back to the keeper, out to the left-back and, with the visitors shutting down five passing options, a sequence of turnovers. The second clip shows how Chelsea, with eight players up, pounce on an attempted build-up by the keeper and how, after a defensive slip, they then create a clear opportunity.

And then there was Bonmatí. Apart from scoring the first goal and provoking the penalty, Grainger pointed out that a significant percentage of her attacking activities were generated by her defensive endeavour. "Apart from her impact when on the ball," Grainger commented, "she was also a key element in defensive actions." Indeed, the Spanish international was involved in pressing moments on 30 occasions and won the second ball seven times – one of them in the lead-up to the opening goal.

"She was outstanding for her out-of-possession counterpressing and her attitude to work," added Grainger. And her analysis is endorsed by the graphic showing Bonmatí's defensive actions spread from box to box and, practically, from corner to corner – 21 in the Chelsea half, 14 in her own and one on the halfway line. The video clips speak volumes for Bonmatí's alertness in winning first and second balls, her technical ability to retain possession in tight situations and the impact of her darting forward runs catching Chelsea in transition mode.

While the titleholders had the edge in terms of the high collective press, they also fared better than their opponents in playing out of it. The evidence is a final graphic that requires a bit of interpretation. The simplest explanation is that, if you're looking for Barça's successes, the top three lines on the right are the ones that count.

After that, if we move over to the left side, we can understand Barcelona's ability to deal with Chelsea's pressure. The graphic shows that both teams' pressing strategies were effective in producing regains – Barça's slightly more so, notably in the number of regains in their own half, often when high pressing forced a long clearance, especially by goalkeeper Hannah Hampton.

Data from the match at Stamford Bridge also highlights Barça's ability to withstand Chelsea's aggressive high press on 50% (21) of occasions (compared with the home team's 37% (20)), either retaining possession (29% (12)) or progressing upfield (21% (9)). The figures, however, need to be coloured by shades of meaning.

Although Chelsea fared less well than their opponents in dealing with pressure, their use of the ball after successfully protecting it was more direct and threatening. Of their 37% success rate in withstanding Barça's pressing, only 9% (5) allowed the team simply to retain possession while 28% (15) signified rapid upfield progress – 7% more than their opponents. In other words, Chelsea were less frequently able to resist the pressure from visitors but, when they did so, they posed a more immediate attacking threat.

Barcelona, nevertheless, emerged as narrow victors of the tussle between two leading exponents of the collective pressing game. "We had a good start," Giráldez said after the win at Stamford Bridge. "We created chances to score. We recovered many balls in the opposition half. We had a good balance with the ball and without the ball. When you are playing away, it is very important to control the game."