Jose Mourinho has reiterated David Luiz's importance to Chelsea as the player continues to be linked with a move to Barcelona.
Luiz, a €25 million signing from Benfica in January 2011, enjoyed his best period in a Chelsea shirt in the second half of last season, often being deployed in a midfield role as the club won the Europa League and finished third in the Premier League.
But now Barcelona are said to be tracking the Brazil international after putting a central defender at the top of their wanted list with four weeks of the summer transfer window to go.
Spanish paper Mundo Deportivo reported on Tuesday that Barca executive Raul Sanllehi was in London on Monday to meet with Luiz's agent, Giuliano Bertolucci, but claimed Chelsea are demanding €46 million to part with the 26-year-old - a fee the La Liga champions will not meet.
Luiz was rested for Chelsea's win over AC Milan in New Jersey on Sunday after suffering a minor hamstring injury in training, having had an extended season at the Confederations Cup in June, from which Brazil emerged victorious.
"David has come back with us fantastically and we have to use his quality," Mourinho told the Daily Mirror. "He has big self-confidence and self-esteem, especially when he comes up from the back with the ball.
"Can he improve defensively? Of course. But it is my job to try always to improve players."