Chelsea have announced the signing of winger Mohamed Salah from Basle.
The capture of the Egypt international, which is subject to him agreeing personal terms and passing a medical, could mean Juan Mata's move to Manchester United will now go ahead.
A statement on chelseafc.com read: "Chelsea Football Club can confirm an agreement has been reached with FC Basel for the transfer of their 21-year-old attacking midfielder Mohamed Salah.
"The move is subject to the Egyptian international agreeing personal terms and completing a medical examination."
Provided the finer details of the move are confirmed swiftly, Salah could make his debut in Sunday's FA Cup fourth round tie at home to Stoke.
He becomes Chelsea's third signing of the winter transfer window, following Bertrand Traore and Nemanja Matic.
So impressed was Jose Mourinho with Salah's performance as Chelsea twice lost to Basle in the Champions League group stages that the Blues boss made his move.
Salah scored in three of the Swiss side's four recent meetings with Chelsea - a goal in each of this season's Group E Champions League wins and also netting in the second leg of last term's Europa League semi-final.
Salah was also being courted by Liverpool, who earlier on Thursday conceded defeat in their pursuit of the winger.
- Video: Salah scores against Chelsea for Basle
Mohamed Salah: Has scored 3 goals in 4 apps vs Chelsea; he has not got a better scoring record against any other team #CFC