Transfer news: Bayern Munich step up interest in Chelsea defender David Luiz Chelsea's David Luiz is the subject of intensifying speculation over a move away from Stamford Bridge with both Bayern Munich and Barcelona believed to be interested in his services. Bayern's new manager Pep Guardiola is a fan of the Brazilian defender's, and he was interested in bringing him to the Nou Camp during his reign as Barcelona boss. Now, settled at the Allianz Arena, Guardiola has identified the defence as an area requiring improvement - especially in the wake of conceding four goals to Borussia Dortmund in the German Super Cup on Saturday. Luiz wouldn't come cheap though, having joined the Europa League champions in January 2011 for £25m from Benfica, and went on to sign a new five-year contract last September. The centre-back, who had been deployed in the defensive midfield role on occasion by former boss Rafa Benitez, could cost Bayern in excess of £40m, which could fend off the Champions League winners from making a move. It was reported in the Catalan newspaper Sport that Barcelona remain interested in Luiz, and they could move for him should they miss out on their number one target Thiago Silva. Alternatively, Paris Saint-Germain could sell Silva to the La Liga champions with a view to bringing his Brazilian defensive teammate to Paris. But Blues boss Jose Mourinho made it clear that he does not want to sell Luiz, despite suggestions from some areas that he doesn't suit the typical Mourinho style. He said, while speaking on the club's tour of Asia: "The potential is incredible, amazing," Mourinho said of Luis. He always has to play. For me he is a central defender. Chelsea also have John Terry and Gary Cahill available at centre-back, with Branislav Ivanovic shifting between right-back and the central role. Either way, the sale would leave Chelsea looking exposed at the back, and they would want to keep Luiz after the promise he has shown in his first two seasons in West London. Luiz missed the pre-season tour of Asia, as he was afforded extra holiday following his participation in the Confederations Cup. He is expected to link up with the rest of the squad today.