Jamie Carragher highlights worrying thing about Kobbie Mainoo he spotted just 20 seconds into Man Utd match

Jamie Carragher was left worried by what Kobbie Mainoo did just 20 seconds into a Manchester United defeat.

On Wednesday evening United booked their place in the quarter-finals of the FA Cup with a 1-0 win against Nottingham Forest.

Casemiro scored an 89th minute winner to set up a mouth-watering clash with Liverpool at Old Trafford next month.

Erik ten Hag selected a strong team at the City Ground, although one notable absentee was Kobbie Mainoo.

The 18-year-old midfielder has been a sure-starter for United since November, and before Wednesday had started 12 successive games for the Red Devils.

However, Ten Hag dropped the youngster to the bench for the FA Cup tie, and Jami Carragher may have explained why.

Speaking on the Stick to Football podcast, Carragher noticed that Mainoo looked a bit lost during the opening stages of United's 2-1 home defeat to Fulham on Saturday.

"I always like to watch the first half of a game because I always think second half, subs come on, you might be winning or losing, things change," the Liverpool icon said.

"The second half might not be the plan, but the first half is the plan of a manager which he’s been building up for two or three days.

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"Straight from the kick off, you must know exactly what you need to do. 'My job’s to press him or his job is to press him'.

"The young lad in midfield [Kobbie Mainoo], it looked like he didn’t really know [what player to mark against Fulham], and this was 20 seconds into the game and I’m thinking, 'You know what to do 20 seconds into the game, especially from a kick-off'."

Mainoo was brought in for the final moments of the win against Forest, and he could well return to United's starting XI for the clash with local rivals Manchester City on Sunday.

If Carragher is right, then it might be that Ten Hag decided to protect the talented but inexperienced youngster from overexposure, particularly if he hasn't fully grasped what he is being asked to do.

Jamie Carragher was speaking on the Stick to Football podcast, brought to you by Sky Bet .