Earlier this week saw Chelsea snap up Cesc Fabregas from Barcelona on a five-year deal. The former Arsenal captain was told he was surplus to requirements at Barca Chelsea were swift, and got a move tied up in a matter of weeks.
But it is a controversial deal. Arsenal fans are aggrieved that their former hero has signed for a London rival, even though The Gunners in fact decided not to sign him.
But it is also a deal not universally popular with the Chelsea faithful. Fabregas has history with Chelsea - and is certainly not a fan favourite at Stamford Bridge.
In particular he has a rivalry stemming back to the 2007 League Cup final with Frank Lampard. He and Lampard, incidentally the man he is replacing at Chelsea, have continued to come to blows when facing off ever since - in a Arsenal or a Barcelona shirt Fabregas and Lampard have had their fair few scuffles.
Lucky Lampard is leaving then - because these two are not best of friends.