Chelsea have reached an agreement to sign Ajax forward Hakim Ziyech in a deal which could cost up to €44 million.
The Morocco international is the first signing coach Frank Lampard has made since joining the club in July. Chelsea were under a transfer embargo and then did not make any signings in the January transfer window.
On Thursday, Ajax tweeted a good luck message to Ziyech alongside a compilation of his best moments, which said: "Hey Chelsea, you have to believe in his magic. And great things will happen."
They then released a statement, which read: "Ajax and Chelsea have reached an agreement for the transfer of Hakim Ziyech. The player will join the Premier League club on July 1, 2020 and will finish the season in Amsterdam.
"The clubs have agreed a deal of €40m. This sum could potentially increase to a maximum of €44m, with variable factors."
ESPN reported in January that Chelsea wanted to sign Ziyech, and while a deal has been agreed, the transfer window has closed so it will be the summer before he joins the club. The club have been interested in the 26-year-old for a while and had to compete with interest from other London clubs Arsenal and Tottenham.
Speaking after Ajax's 3-0 cup win over Vitesse Arnhem, boss Erik ten Hag said he was happy no player had left the club in January.
"A transfer was coming, we expected it to happen," the manager told Fox Sports, when asked about reports Ziyech would join Chelsea. "And I actually already expected this one or two years earlier.
"And each time it was: 'Wow, he stayed again.' We are just happy that we will still have him until the end of the season."
Sources have told ESPN that Ajax successfully negotiated a new contract with Ziyech in the summer, which removed a €30m release clause.
Ziyech was a key part of the Ajax team which eliminated Real Madrid and Juventus en route to the Champions League semifinals last season and also won the league and KNVB Cup in the Netherlands.
Chelsea have met Ajax twice this year in the Champions League group stages with Ziyech having started both games. The Blues won the first leg 1-0 while the second leg in Amsterdam ended in a 4-4 draw.
He has scored nine goals across 28 Eredivise and Champions League games. Ziyech was voted the club's Player of the Year in each of the past two seasons and had contributed the league's most assists in four of the past five campaigns.