United appeared to have abandoned their pursuit of Fabregas last week following comments by the 26-year-old which suggested he had no intention of leaving the Nou Camp two years after returning to his hometown club from Arsenal.

After Fabregas had claimed in Malaysia during the Spanish champions’ Far East tour last Friday that he was “very happy at Barcelona” United responded by issuing a statement insisting they “completely respect everything Cesc has said”.

However Moyes and senior figures at Old Trafford remain convinced that Fabregas continues to harbour doubts over his first-team prospects at the Nou Camp and that the next two weeks will be pivotal in their attempts to sign the player.

It is also understood that Barcelona have indicated to United a figure which would prompt them to consider selling Fabregas but Moyes is keen to assess the situation before sanctioning another offer following Barcelona’s rejection of bids worth £26 million and £30 million from Old Trafford.

With Fabregas facing time on the sidelines with sprained ankle ligaments — an injury which ruled him out of Spain’s friendly against Ecuador in Guayaquil on Wednesday night — Moyes is ready to monitor the player’s involvement with Barcelona in their fixtures leading up to the Sept 2 transfer deadline before lodging a third bid.

Fabregas could be back for Barcelona’s La Liga opener against Levante on Sunday and should be fit for the first leg of the Super Cup encounter with Atletico Madrid next Wednesday.

Following the Atletico tie Barcelona face Malaga and Valencia in the league either side of the second leg of the Super Cup and United believe that Fabregas’s contribution to those fixtures will decide the player’s future.

While talking of his happiness at the Spanish Catalan capital and that "triumphing in Barcelona is what I have been hoping for all my life" Fabregas also admitted in Malaysia to being "flattered" by United’s interest and that his priority was to play first-team football.

Comments by new Barcelona manager Tata Martino that Fabregas would be a key player in his plans have been welcomed by the midfielder but there is also a concern that the £53 million signing of Brazil international Neymar will ultimately lead to Fabregas losing his place in the team.

With Spain due to defend the World Cup in Brazil next summer Fabregas is known to be determined to ensure that he plays regular first-team football in order to avoid dropping out of Vicente del Bosque’s team.

United are aware however that prising Fabregas from Barcelona remains a difficult challenge and that there is no guarantee that a third bid will prove successful despite the indications from the Nou Camp of a potential transfer fee. United chief executive Ed Woodward having made it clear that Wayne Rooney will not be sold this summer is also keen to deliver a statement of intent in his first season at the helm by securing the services of a player in the Fabregas bracket.

Moyes is expected to return to former club Everton with bids for Leighton Baines and Marouane Fellaini in the coming days but there remains a desire at the highest level at United to secure a marquee signing before the transfer window closes.

On Wednesday Everton manager Roberto Martinez played down the prospects of a United bid for Baines saying one club had put in a “final offer” before his side left for a tour of Austria.

“They put something over and the valuation wasn’t anywhere near the quality of Leighton Baines” Martinez said.