Barcelona have concerns over a £50m tug-of-war between Manchester's Premier League giants for defender Samuel Umtiti.
Notorious Spanish rumourmongers Don Balon claim that both United and City could tussle it out for the centre-half in January if the duo opt to activate the release clause fee in Umtiti's contract.
Virgil van Dijk's £75m transfer to Liverpool has set the transfer market alight days before it is even open, and City in particular have been left dismayed over missing out on the Dutch international.
Pep Guardiola was a firm admirer of Van Dijk before the ex-Southampton star decided to head to Anfield, and may now opt to make a move for Umtiti to bolster his defensive ranks.
The Premier League leaders will, however, face competition from United for his signature as Jose Mourinho eyes his own defensive reinforcements next month.
Mourinho has gone on record stating that United's £300m spending over his 18-month tenure at Old Trafford has not been 'enough' to truly compete with Guardiola's unrelenting City outfit.
The Portuguese boss has now reportedly turned his attentions to land Umtiti due to the 'modest' nature of his release clause fee, and amid suggestions that he has been left underwhelmed by Victor Lindelof's form since his move from Benfica in the summer.
Both Mourinho and Guardiola have injury problems at the back with Eric Bailly and Vincent Kompany sidelined, and the opportunity to try and lure Umtiti away from Catalonia would be too good to resist.
Barca boss Ernesto Valverde, though, hopes that the offer of an improved contract will be good enough to sway Umtiti into staying at Camp Nou and help his team reclaim the Spanish top flight title from rivals Real Madrid this season.
The 24-year-old, who still has three and a half years to run on his current deal, has turned out 62 times for La Blaugrana since his big-money switch from Lyon for around £20m in July 2016.