Stopping Barcelona has been beyond everyone in La Liga for a good while now. They have not lost in Spain for 31 weeks.
But there have been times when they’ve looked vulnerable.
Sportsmail looks at the potential weaknesses Chelsea can exploit.
Chelsea manager Antonio Conte has a tough task on Tuesday when his side face Barcelona
The Watford way?
Chelsea might find part of the answer 20 miles up the M1 at Vicarage Road. Watford coach Javi Gracia did well against Barcelona when he coached in Spain. In the 2014-15 season, Barca won the treble but his Malaga team beat them 1-0 at the Nou Camp and drew with them at home.
What was his secret?
He wasn’t concerned with Barca having the ball in wide areas or in their own half. The idea was that if you get drawn into wide areas, then you are leaving space in front of goal. Make things tight and congested in the penalty area and don’t get stretched. It worked.
Watford boss Javi Gracia had an excellent record against Barcelona while in charge of Malaga
Haven’t Barca changed?
They still play a very high line. You need strong runners who can cover the huge distance they leave behind their defenders. It’s not a game for a centre forward with a lovely touch but no pace. It’s more a job for a fast winger who can get behind the full back and make quick diagonal runs at goal. The best recent example was John Guidetti’s goal for Alaves in January, when Samuel Umtiti was ridiculously high up the pitch and couldn’t get back.
But their formation is now 4-4-2, isn’t it?
As much as you can nail down their formation then yes. When they go forward there is always a third player in attack, be it Paulinho or Andres Iniesta from midfield, or Jordi Alba or Sergi Roberto arriving from full back, but they fall into a 4-4-2 without the ball. Maybe that’s why they conceded only once in the group stage.
John Guidetti scored against Barcelona in January by exploiting their ridiculously high line
It’s still a big change from 4-3-3…
Yes. Neymar has gone and no one has directly replaced him. Jordi Alba has a lot more licence to get forward from left back and often ends up in ‘Neymar territory’. He now links up with Lionel Messi as well as Dani Alves used to.
What have other teams tried?
Espanyol defended very deep in the first half in two cup games. In the second half they put on a second forward and took several steps up the pitch. They drew the first leg 1-1 but Barca won the second 2-0.
Others sat on Sergio Busquets to make it more difficult for Barca to pass out from the back, forcing them to go long.
Where does Messi play?
He starts up front alongside Luis Suarez but comes deeper looking for the ball, especially when things don’t go well. The question then is: ‘should you follow him?’
Girona employed a man-marker earlier in the season. But while Manchester City loanee Pablo Maffeo did a good job, Girona lost 3-0.
Messi’s role has changed slightly since Barcelona switched to a 4-4-2 formation this season
What tactics have been used?
Espanyol defended very deep in the first half in the cup games. In the second half they put on a second forward and took several steps up the pitch.
They drew the first leg 1-1 but Barca won the second 2-0. Others sit on Sergio Busquets to make it more difficult for Barca to pass out from the back, forcing them to go longer where Suarez can find it hard to hold the ball up on his own.
Eibar and Real Madrid have tried it — but both lost.
Some teams have had some joy from having a player sit on midfielder Sergio Busquets
So, no matter what, Barca still win…
Well Eibar and Espanyol did not have N’Golo Kante to track Messi or Eden Hazard and Pedro on the end of quick counter-attacks. Antonio Conte has more resources at his disposal — and Barca are well aware of that too.
Eibar and Espanyol were not able to turn to someone like N’Golo Kante to track Messi
They also do not have a player of the quality of Eden Hazard to spearhead their attacks