This month's transfer window burst into life on Thursday as Chelsea agreed a deal to sign FC Basel's young Egyptian winger Mohamed Salah.
It seemed a great coup for the Blues: the 21-year-old international is Basel's star player, and was the key man in the Swiss team's wins over Jose Mourinho's side during the Champions League groups stage in the autumn.
Basel played Maccabi Tel Aviv in the qualifying rounds of the Champions League last summer - and Salah appeared to be very unsure about the idea of shaking hands with players representing a side from a country which has been at loggerheads with his native Egypt for generations.
In the first leg, in Switzerland, Salah seemingly dodged the issue by conspicuously changing his boots on the sidelines while the handshakes were going on.
The player was criticised for his actions in the Swiss press, but did not back down - and reportedly even asked to be left out of the side for the return match in Tel Aviv.
Salah eventually relented via a statement released to the press - but the wording he chose only served to stoke the controversy further:
"I will fly to Israel. Football is more important than politics and it is my job. In my thoughts I am going to play in Palestine and not Israel, and I am also going to score and win there. The Zionist flag won’t be shown in the Champions League."
His prediction proved fairly accurate: he did score, and the thrilling 3-3 draw on the night was enough to put Basel into the group stages of the tournament.
But all eyes were on him before kick-off: would he again refuse to shake the hands of Israeli players?
TV cameras zoomed in mercilessly on Salah as the teams lined up for the handshake - and the 21-year-old proceeded to fist-bump his opponents rather than offer the more traditional handshake.
You can make whatever you will of Salah's actions - but the issue for the player isn't what you think. It's what Roman Abramovich thinks.
That's because Chelsea's billionaire owner is himself Jewish, and a generous supporter of a number of projects in Israel. Will he be angry that Salah has beeen signed up? Will there be an uncomfortable silence whenever the two bump into each other on match days? Or will Abramovich, like his new player, decide to try and keep sport and politics apart? Only time will tell.
Salah fistbumps his opposite numbers in Tel Aviv