Joel Was Right
Member
It means Barce have to accept the Arsenal bid, he doesn't have to go to Arsenal above United, Barce accept and let the player decide...
Technically, I don't think they're even meant to enter negotiations with another club before notifying/inviting the club that have first refusal, otherwise it would just be a normal bidding process.
I've read from somewhere that the specific clause relating to Fabregas is triggered only if the player asks for Arsenal, and then a pre-agreed transfer fee would be enough to secure his signature.