Oscar (R)
Chelsea have confirmed the transfer of Brazilian midfielder Oscar. Reports suggest a fee of £25m has exchanged hands

Chelsea have confirmed the transfer of Brazilian midfielder Oscar, according to a statement on the club's official Web site. The notice does not indicate a transfer fee but reports suggest it was around £25m.

The former Internacional player is presently in London, as part of Brazil's men's football team for the Olympics and played in the 2-0 friendly win over Team Great Britain. Oscar is Chelsea's fourth signing of the summer, following deals for Belgian brothers Eden and Thorgan Hazard and German Marko Marin.

Oscar, 20, is a graduate from the Sao Paolo academy and was a member of the Brazil U17 side that won the World Championships. He transferred to Internacional in 2010 and made his debut for the Brazilian senior side in September.

Oscar had been strongly linked to the Blues all summer long and was quoted as saying moving to Chelsea would be a "dream".

"If I go to Chelsea, it will be a dream. It's a big club in Europe. I'm sure that I will have a great Olympics and I will stay in Chelsea. If it doesn't happen, I will go back to Internacional [in Brazil] to keep doing my work," the youngster said.

Meanwhile, the Blues' veteran midfielder has challenged his team mates to step up their game and respond to the raft of new faces coming to Stamford Bridge.

"We are playing for our season at this stage, regardless of last year we have to perform at a high level to stay in the team. This year we are a different team with new players coming in. It will have to settle down," Lampard explained, "But there's an excitement about our team this year. Last year we proved ourselves to be a great team and a great unit with what we achieved."

The Blues are leaving little to chance, as they prepare for a defence of their Champions League crown and a better assault on the Premier League title. However, it will be interesting to see how well their new signings adapt to the rigours of the English game, given that all of them are unproven in England and have, between them, cost tremendous amounts of money.

Chelsea start their Premier League campaign away to QPR on 18 August.