Jose Mourinho, back for a second spell as coach of Chelsea, set up his first signing when the Europa League winners agreed on Thursday to buy winger Andre Schuerrle from Bayer Leverkusen.
"Chelsea Football Club and Bayer 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," the Londoners said in a statement.
The transfer fee was not disclosed but media reports have put it at 18 million pounds ($28.2 million).
German international Schuerrle scored 11 Bundesliga goals last season.
The signing of Schuerrle could mean that fellow German Marko Marin, a disappointment since joining Chelsea from Werder Bremen 12 months ago, Victor Moses or even Juan Mata could be heading for the Stamford Bridge exit door.
Spain midfielder Mata has become a big crowd favourite in his two years in London, scooping two successive Player of the Year awards at the club.
Media reports have suggested Mourinho may move him on although the former Real Madrid, Inter Milan and Porto coach told his first news conference back at Stamford Bridge that every Chelsea player would be given a chance to prove his worth.
"I need to work with the players and not commit injustice," the 50-year-old Portuguese said on Monday.
"I need to give them a chance, be fair with them. After that we'll have time to make decisions."
Mata is now on Confederations Cup duty in Brazil with world and European champions Spain.
Mourinho, who was also in charge of Chelsea from 2004-07, will find out which opposition team he will start the season against when the Premier League announces the new fixture list on Wednesday.
Photograph: Joern Pollex/Getty Images
Ballack farewell overshadowed by Schuerrle Chelsea deal
Euro soccer: Arsenal, Milan book Champions League berth
Bayern edge past Gladbach, Dortmund lose
Dortmund hit six and Bayern four in easy wins
Bayern risk undermining harmony with big-name signings