Former Manchester United defender Gary Neville believes that Jose Mourinho's rise from being an assistant under Louis van Gaal at Barcelona is the Dutchman's biggest achievement.

The Chelsea manager has won two Champions League titles with Porto and Inter Milan, while winning the league at Portugal, England, Italy and Spain, a remarkable achievement for any manager in this modern age.

Van Gaal has been a revelation himself, stamping his mark with Ajax, then moving to Barcelona and Bayern Munich, where he has scripted history and laid a platform for the teams to thrive.

The two stalwarts shall face off in an epic battle at Stamford Bridge on 18 April, in a match which has the potential to decide the title. A win here for Van Gaal will see his side move to within four points of the league leaders, who have Arsenal and Liverpool to face in the next few games.

However, a loss will put an end to the debate and unless Chelsea make a goof up of epic proportions in the next few games, it will be yet another jewel in Mourinho's illustrious crown.

Neville, who has himself played under another managerial great in the form of Sir Alex Ferguson, believes that this game will be directly influenced by the philosophy of the managers, more than the 22 players on the pitch.

"A former Tory leader once said when asked what their greatest achievement was: "New Labour". I can imagine Louis Van Gaal, when answering the same question from a group of journalists, peering back from his desk and responding: "Mourinho."" said Neville in his column with the Telegraph.

"I am loath to pitch leader v leader without good reason in a football contest where 11 v 11 have the ultimate say, but Chelsea v Manchester United is a match where I feel that the coaches will have a huge impact on the spectacle and outcome of this game.

"Neither Mourinho or Van Gaal are where they would ultimately want to be at the moment, but both are on a journey and heading in the right direction," he concluded.