Roy Keane has questioned why Cristiano Ronaldo was omitted from Manchester United's squad for Sunday's derby showdown with Manchester City.

Ronaldo leads the scoring charts for United this term with 15 goals across all competitions, but he played no part against Premier League leaders City at the Etihad Stadium.

Ralf Rangnick put the Portugal international's absence for the contest down to a hip flexor injury that kept him out of training on Friday.

But former United midfielder Keane suggested there may be other reasons behind the five-time Ballon d'Or winner being left out by Rangnick for such an important game.

"There seems to be more to the Ronaldo story when a manager comes out and talks about a hip flexor... I don't get it," Keane told Sky Sports ahead of the match. 

"We talk about Ronaldo being a machine and very rarely getting injured but every now and again he comes out with that... a hip flexor? It doesn't add up to me.

"It's a surprise to hear Ronaldo has a hip injury but United have pace, quality. They still have important players and they still have to come out and play with pride."

Ronaldo had played in 30 of United's 37 games this term prior to the City game, a tally bettered only by Jadon Sancho (31), David de Gea (35) and Bruno Fernandes (36).

United had won 11 of the 20 Premier League games Ronaldo had featured in before Sunday, compared to two wins from the seven games he has not played a part in.

Luke Shaw and Raphael Varane also missed the City match after testing positive for coronavirus, while Edinson Cavani failed to recover from injury in time.