Juan Mata's English lessons at Chelsea could leave Barça regretting pass

Overlooked by Guardiola last summer, his creativity will be crucial to Chelsea tonight

Juan Mata: Chelsea's No 10 is a player very much in the Barça mould (Getty Images)

To judge by the attitude of Cesc Fabregas and Pep Guardiola yesterday, recent conversation among the greatest football team in the world has not been about how their opposition in tonight's Champions League semi-final have evolved. Rather it has been about how Chelsea have stayed the same: obstinate, unyielding, reluctant to let go of the formula that has delivered the club its glory years.

Fabregas said it the most bluntly, talking about a Chelsea team that had "gone back" to the way it knew best after the Andre Villas-Boas interregnum. Guardiola spoke in more general terms, praising the longevity of the club, its "soul", which sounded like a polite way of saying that this group of Chelsea players had been around for a bloody long time.

It felt that way at times yesterday, especially with Frank Lampard at the press conference table talking about his 11th season at the club and discussing the old question of when Chelsea were at last going to win a competition in which they have reached the semi-finals six times in nine years. You could have been at any Chelsea Champions League press conference of the last five years.

Lampard is likely, but not guaranteed, to start the game tonight. The difference this time is a player who will be asked to shoulder more of the creative burden than any new signing of the last few years. Juan Mata is certain to play against Barcelona, the club for whom he almost signed last summer before he joined Chelsea for £23.5m

No outfield player has made more appearances for Mata for Chelsea this season – 42 starts and five more as a substitute – and in a team that lacks sparkle, he is increasingly relied upon as the creator. Successive Chelsea teams have never really cherished the ideal of a traditional No 10 playmaker – just ask Mata's predecessor in the shirt, Joe Cole.

Lampard, with 16 goals, has scored four more than Mata this season, but the younger man has got some crucial goals, and not just the one that did not cross the line against Spurs in the FA Cup semi-final. In a 4-2-3-1 formation it is Mata who slots in just behind the central striker. On Sunday that striker was Didier Drogba, but there is every chance it could be Fernando Torres tonight.

Mata, 23, said in yesterday's Spanish newspapers that he thought it would be Torres who would start ahead of him in attack against Barcelona. "Fernando nearly always scored against Barça when he was at Atletico Madrid," he said. "He really wants to play this one."

Chelsea have lost just two of their eight encounters with Barcelona in the Roman Abramovich era, the last of those was more than six years ago, and they need to win tonight to have any hope of getting through. "Winning 1-0 or 2-0 in the first leg would be the ideal," Mata said. "I think we can score there. The most important thing is to score and if we keep a clean sheet then even better.

"If there is one ground where Barça have not had it easy it is Stamford Bridge [they have won once there in those eight games, back in February 2006]," he added. "For the dimensions [of the pitch], for the fans being close to the pitch, the atmosphere." Asked whether his team could cope with being denied the ball, he warned that might not be the case. "Maybe we will have more possession than people think."

Mata is the one who never quite made it at the big two in Spain. He was an academy player at Real Madrid but they let him go to Valencia. There was interest in him from Barcelona, who eventually opted to sign Alexis Sanchez last summer. He has 16 caps for the Spain senior team, and five goals, but he will not be in the first XI at the European Championship this summer unless injuries change the picture.

Nevertheless, his progress has been watched with interest in Spain, where the feeling is that Torres was improved – at least when he was at Liverpool – by his time in the Premier League. Mata was signed by Chelsea in the summer when they realised that their pursuit of Tottenham's Luka Modric was not going to be a success and, although he was originally regarded as a winger, it is as a central playmaker that Mata feels most comfortable.

It was for that reason Villas-Boas gave him the No 10 shirt. Chelsea teams of recent years have never truly accommodated a No 10-style player in the past like Mata. Michael Ballack did it to some extent, but became more of a defensive midfielder in his time at the club. In the era of Lampard and Michael Essien it has been about power and getting the ball forward quickly.

"I believe a lot in Stamford Bridge," Mata said. "The noise of the supporters is important. Barcelona will not be comfortable." He is also not affected by the nine years of coming up short against the likes of Barcelona, Liverpool and Manchester United. In a season in which Oriol Romeu has mysteriously disappeared from the first-team picture, and Romelu Lukaku is not even in the Champions League squad, Mata is the year's breakthrough attacking player.

Asked yesterday whether he ever felt it was inevitable that Chelsea would win the Champions League one day, Lampard said that he "wished it was". "You're a bit older every year. As a team, you appreciate what you want more. Semi-finals don't come round every year. They won't be there for ever." That is certainly the case for the old Chelsea that Fabregas recognises, but Mata has time on his side.

Key confrontations: Where tonight's match will be won and lost

John Terry v Lionel Messi

How do you stop the best player in the world? Messi's speed, movement and dribbling abilities are a terrifying prospect for any centre-back. Terry will have to keep his composure – and refrain from diving in when isolated against the Argentine.

John Obi Mikel v Xavi

The Spaniard is the chief orchestrator in Barcelona's midfield – especially if he is given space. Mikel will be deployed to put pressure on him, and needs to concentrate on his task. If and when Xavi does wriggle free, his incisive passing could prove devastating.

Fernando Torres v Gerard Pique

When Chelsea do get the ball, they will look to spring their attack to take a goal or two to the Nou Camp next week. Torres will have to be patient, and will likely have to hold off Pique, while waiting for the support of Juan Mata and Ramires to hurt the visitors.