Manchester United face competition for Cesc Fabregas from three Premier League rivals.
Sources understand United's opening bid of £25million, communicated to Barcelona on Monday, has sharpened interest from Arsenal, Chelsea and Manchester City.
And Arsenal must now decide whether to follow up their initial interest and take advantage of a clause in Fabregas' contract allowing them first refusal on their former captain, who rejoined Barca in 2011 following eight years in north London.
For his part, Fabregas has repeatedly said he is happy in Catalonia, although Sky sources are indicating he would be open to a move elsewhere if Barca accepted a bid.
That has not happened yet, and United are still awaiting a response to their offer, which was lodged as David Moyes steps up his chase for a creative influence.
Barca, meanwhile, may be reluctant to lose another midfielder so soon after Thiago Alcantara's recent move to Bayern Munich.