Jose Mourinho on Thursday made his first signing since his reappointment as Chelsea coach, with the arrival of Germany forward Andre Schurrle from Bayer Leverkusen.
"Chelsea Football Club and Bayer 04 Leverkusen have reached an agreement for the transfer of Andre Schuerrle, subject to the completion of legal documentation and related matters, including personal terms and passing a medical," a statement on chelseafc.com said.
No further details were immediately available but reports in Britain suggested he has been signed for some £18 million (21 million euros, $28 million).
Schuerrle has been a long-term target for Chelsea since they won the 2011/12 Champions League.
Leverkusen's director of sport Rudi Voeller said in April that the west London club rejected a 25-million-euro offer for the player just after their European triumph.
Schuerrle, 22, began his career at Mainz, before transferring to Leverkusen in 2011, where he made 65 appearances and scored 18 goals.
He has played for Germany at under-19 and under-21 level and made 24 appearances for the senior side, scoring seven goals.
Mourinho was reappointed as Chelsea manager earlier this month after stints in Italy and Spain coaching Inter Milan and Real Madrid.
The 50-year-old Portuguese, who previously managed Chelsea between 2004 and 2007, told reporters this week that he wants to leave a long-lasting legacy at the club.
He has inherited a squad rich with talented young players such as Eden Hazard, Oscar and Victor Moses, but also faces awkward decisions about how to handle the old guard.
Striker Fernando Torres belatedly found his feet under interim boss Rafael Benitez, scoring 22 times in 64 games, but Mourinho hinted that he may be allowed to leave the club in the close season.