Former England international Gary Neville has voiced his admiration of Barcelona, and feels that the Catalans have redefined football with their inventive style of play.
Barcelona have reached three out of the last six Champions League finals, and Neville feels that they are the second 'great team' of his time after Arrigo Sacchi's AC Milan.
"The first truly great team I watched was the AC Milan line-up of the late eighties and early nineties. They dominated the game with five European Cup finals in seven years and had great players," Neville says in his Daily Mail column.
"Now, 20 years later, we are witnessing in Barcelona, who face Chelsea in the Champions League semi-finals this week, the next great team. A truly great team not only wins multiple European Cups but also redefine football with new ideas, a new improved way of doing things.
"The level at which this Barcelona side relentlessly close down opponents high up the pitch is something I've never seen before. They win the ball back with the speed of a gun."
Neville then looked ahead to the Champions League semi-final between Chelsea and Barcelona, and stressed that the Premier League side face a tough task.
"Chelsea have a monumental problem in a two-legged semi-final. Because even at their best, they won’t be good enough to beat Barcelona without unforeseen help.
"Barca's system of playing without a centre-forward allows Lionel Messi, the greatest player of modern times and arguably all-time, to roam and find the weakest link in any defence.
"Messi is unplayable and Chelsea will have to stop the best three midfielders in the world, Xavi, Iniesta and Fabregas, to stop him getting the ball. Messi will sniff out where Chelsea are weakest and play in those areas."
Wednesday's first leg at Stamford Bridge kicks off at 20.45CET.