The Algeria international put Pep Guardiola's treble-chasing side ahead with a penalty late in the first half before striking twice more after the hour.

Championship high-flyers United failed to trouble the imperious City, who made light of their draining schedule in the week they also reached the Champions League semi-finals with a commanding performance.

It was their 11th win in 12 games and they now go into Wednesday's crucial top-of-table Premier League clash with leaders Arsenal with considerable confidence and momentum.

The loss made for an anti-climatic end to the Blades' superb run in the competition but their main goal of promotion back to the top-flight should soon follow.

Guardiola made six changes but retained the prolific Erling Haaland, who has scored 48 goals this season, in attack.

Surprisingly, however, it was not the Norwegian who dominated the game but one of the players brought into the side - Mahrez.

United were without their two City loanees in Tommy Doyle and James McAtee and the pair were missed as they struggled to gain a foothold in the game.

Yet the outcome could have been different had the Blades taken their one meaningful chance of the game in the second minute.

Iliman Ndiaye should have scored when the ball fell to him following a corner but he shot straight at Stefan Ortega.

The Blades were to rue that miss as they saw very little of the ball thereafter.

To their credit they defended stoutly and initially limited City to few clear-cut chances but it seemed only a matter of time before Guardiola's men would break through.

Haaland gave United a warning when he rifled in a shot from 35 yards but the whistle had already been blown for a foul.

Mahrez curled a shot wide and Julian Alvarez forced a good save from Wes Foderingham before John Fleck diverted a Bernardo Silva cross dangerously close to his own goal.

United threatened again when Jack Robinson took aim from distance but Ortega was not troubled.

City went ahead just before the interval after Daniel Jebbison brought down Silva in the area.

Mahrez, assuming penalty-taking duties after Haaland fired over against Bayern Munich in midweek, confidently sent Foderingham the wrong way.

The second half continued in much the same fashion, with United struggling to gain any meaningful possession.

City gradually turned the screw and they doubled the lead just after the hour as Mahrez seized the ball in midfield and was allowed to run through unchallenged. With no sign of a tackle as he reached the box, he coolly slotted past Foderingham.

He completed his treble five minutes later. Again the United defence were helpless, this time allowing Jack Grealish to clip in a ball from the left. Mahrez met it with a sweet strike from in front of goal and, despite getting a hand to it, Foderingham was unable to keep it out.

Guardiola then began to turn his attention to Arsenal and made a number of changes. City confidently played out time and will now return to the national stadium in June to face rivals Manchester United or Brighton.

Fall of Wickets	Player	Score	Overs	Bowler	Out
2	Sarel Erwee	11	3.4	Beuran Hendricks	Catch OUT
1	Tshepang Dithole	11	2.5	Nandre Burger	Catch OUT

Finished CSA 4-Day Series Division 1