Chelsea have signed midfielder Nemanja Matic from Slovakian club MFK Kosice. The 21-year-old, who has two caps for Serbia, has agreed a four-year contract at Stamford Bridge. Claudio Pizarro, meanwhile, has left the club to join Werder Bremen.
The 6ft 4in midfielder has cost Chelsea €1.75m and joins compatriot Branislav Ivanovic at the Bridge. Matic told the club's official website: "I know a lot about Chelsea, I have been following them.
"I play together with Branislav in the national team and have spoken to him about Chelsea. The first time when I met him to play in the national team I asked a couple of questions."
He added: "I am a solid midfielder, I have a lot to offer and for sure to progress and I will show everyone why I am at Chelsea. I am a central midfielder and I know I am not well known but I have physical power and I am quite a technical, left-footed player."
Matic had a trial at Middlesbrough in January. "I was there in the winter, when I came it was winter in the north of England so it was not very nice, but the squad was OK and I liked it."
He will not be available immediately as he is recovering from a broken metatarsal suffered at the European Under-21 Championships in June.
Werder Bremen have re-signed Pizarro after the Peruvian enjoyed a successful loan spell there last term.
Pizarro, who also spent two years at Bremen earlier in his career, helped them win the German cup and reach the final of the Uefa Cup.
The 30-year-old returned to Stamford Bridge at the end of the campaign, but appeared to have little chance of first-team football with Nicolas Anelka, Didier Drogba and Salomon Kalou for competition.
Pizarro, who did not feature in Carlo Ancelotti's squad for their opening 2-1 win over Hull on Saturday, flew to Bremen last night to seal the transfer.
Pizarro joined Chelsea in the summer of 2007 on a free transfer from Bayern Munich but soon found himself out of the picture when manager Jose Mourinho left the club and Anelka was recruited.
"I am happy to be back as I wanted desperately to return to Werder," Pizarro said.