Man City are sweating on the fitness of Ruben Dias ahead of the derby

Manchester City are sweating on the fitness of star defender Ruben Dias ahead of Sunday's derby.

Dias was substituted at half-time of Tuesday night's 2-0 FA Cup victory at Peterborough United with what Pep Guardiola described as a leg injury.

The 24-year-old is undergoing tests and City are awaiting those results before they can ascertain the severity of the problem.

Although Guardiola rotates his team heavily, Dias has started all but three of City's Premier League games this term and his absence against Manchester United would be a blow to the champions.

Dias is seen as a leader at the back and was voted into the club's five-man leadership group last summer, taking on captain's responsibilities if Fernandinho and Ilkay Gundogan are absent.

Video: Blood Red: Diogo Jota And Roberto Firmino Injury Update | Liverpool Train Ahead Of Leeds United (Liverpool Echo)

Blood Red: 'INCREDIBLE MENTALITY' - Klopp on Liverpool & This Seasons Aspirations

Blood Red: Liverpool Update Champions Wall after winning Record NINTH League Cup

Liverpool Players Celebrate League Cup Win in Wembley Changing Rooms

Royal Blue Podcast: US Based Everton Fan Astro Special

Blood Red: 'BEST NO.2 IN THE WORLD' - Jurgen Klopp on Caoimhin Kelleher Following Carabao Cup Win

Liverpool v Norwich FA Cup 5th Round Preview

Blood Red: Joe Gomez Starts | Team Selector | Liverpool vs Norwich City

Blood Red: Liverpool Fans React To Kepa Penalty Miss At Camp & Furnace

Blood Red: Jurgen Klopp provides Thiago Alcantara Injury Update

Blood Red: Can Liverpool Win the Quadruple? | Blood Red Podcast Clip

Nathan Ake was also forced off against Peterborough, with Guardiola set to partner Aymeric Laporte and John Stones together should Dias not prove his fitness. 

City have