Barcelona's surprise 2-0 win at AC Milan on Wednesday has left all four La Liga Champions League representatives on the back foot ahead of next month's Last 16 second legs, and in danger of missing out on a place in the quarter-finals.
Should they all fail, it would mark the first time since 2005 that a Spanish side will fail to reach the last eight — the last time was when Barca and Real Madrid fell in the Last 16 after Valencia and Deportivo La Coruna were eliminated in the Group Stage.
Barca are in the most precarious position after a superbly organised Milan successfully repelled wave after wave of attacks from the 2011 winners and stopped the free-scoring Lionel Messi from producing a single shot on target.
So how did Milan beat Barcelona? Firstpost takes a look at five factors that made the difference.
Milan didn't just park the bus
It wasn't like Chelsea last year. They lost their captain in the 37th minute against a team that is/was in the eyes of many the best team the world has ever seen — and then they shut shop with a valiant effort. It’s rare to see ten players produce such a dogged, determined effort as the Blues did, and it’s important to remember that they did it in hostile territory.
Milan, however, were never as desperate. They were playing to a plan. They didn't worry so much about Barcelona's wing play, they concentrated on the centre and formed a wall of mobile, alert defenders. And every time they got the chance, they broke with pace. It was a cold, calculated tactic and it was typically Italian.
Barcelona had an off-day in both instances but then it wasn't Chelsea or Milan's fault.
A stat to show how well Milan did: Barcelona had no completed through balls. Iniesta only attempted one. The team only attempted four.
Messi is tiny, he is quick, he is slippery. He is everything that defenders hate and he has the ability of popping up into right areas just when the opposition thinks they have dealt with him. But yesterday, he was off-colour.
Messi had just one touch in the penalty area and even then he was quickly surrounded by three players. Keep Messi off balance and you keep Barcelona off balance. He dominates goal-scoring for them but shutting him up is never easy.
Just look at the graphic below to see just how well Milan did it.
Les ballons touchés par Messi face à l'AC Milan. http://t.co/wOsbyJtO3f
— OptaJean (@OptaJean) February 20, 2013
Ricardo Montolivo was a star
“It went well and we played the game we had to, as we were prepared for them to keep possession and therefore we shut down the spaces to make it sterile,” Montolivo told Mediaset after the game.
He was being modest. Montolivo had a brilliant game. Massimo Ambrosini's defensive role allowed him to make plays even from the deep. His long balls showcased vision and also meant that Barcelona's full-backs were never quite sure of what they should do.
Add to that the emergence of Sulley Muntari in the second half. Largely invisible in the first 45 minutes (apart from a long-range volley), Muntari was everywhere in the second — his run for the second goal from deep was proof of that.
Lack of invention
Andres Iniesta was not on his game. Xavi is the engine but the flair often comes from Iniesta and Messi. With Iniesta struggling, the onus was on Messi to produce the goods but for once he cracked up under pressure and some expert marking. If you keep trying to play short passes, eventually the opposition will work out a counter. There has to be some variety — and we didn't see it.
Here's a telling stat: Their one shot on target was from 30 yards out. Xavi took it.
Stephan El Shaarawy
His control in the first half wasn't quite up to mark — a bad touch let him down when he had a good scoring chance after 14 minutes — but in the second half — he was a constant threat. His pace up the left wing was pretty good as well but it was the manner in which he tracked back to pick up Dani Alves that really set the tone for Milan. He's just 20 but he displayed great maturity — despite that haircut. It showed that they were all in it to win and were in no way overawed by the opposition.
Barcelona have only once before lost the first leg of European tie 2-0, against Anderlecht in 1989-90. The return game at the Camp Nou ended 2-1. It won't be easy for Milan at the Nou Camp but they will go there knowing they have the edge and a plan that works.
The second leg is on 12 March.