City, who started the game with a two-goal cushion, took care of business early with first-half goals by Manuel Akanji, Julian Alvarez and Erling Haaland.

Akanji scored with City's first chance, volleying in Alvarez's corner in the fifth minute.

"I saw the ball coming. It was perfect for my foot," Akanji told TNT. "I was really happy about it. It was our aim to score early. The first two goals in the first half made it easier for us. We tried to do our best and did what we had to do."

Alvarez scored his own four minutes later, thanks to calamitous goalkeeping by Kamil Grabara, who let the City forward's shot slip through his hands seconds after Rodri pinged an effort off the crossbar.

Former Southampton player Mohamed Elyounoussi pulled one back for the Danish champions in the 29th minute but City's goal-scoring machine Haaland slotted home a low, hard shot through two defenders seconds before halftime, his 29th goal of the season across all competitions.

Rico Lewis had a late chance for a fourth City goal but his shot hit the bar.

City will find out their quarter-final opponents in the draw on March 15.

"We feel good right now," Akanji said. "We're confident going into the next round. We are one of the favourites but have to prove it."

City reached the quarter-finals for the seventh straight season.

With a trip to Liverpool in a top-of-the-table Premier League clash to come on Sunday, Guardiola made seven changes to his side that beat Manchester United 3-1 in last Sunday's league derby with neither Kevin De Bruyne nor Phil Foden playing.

Haaland was taken off late in the game, wrapping 18-year-old substitute Jacob Wright in a hug as he left the pitch.

City are a point behind Liverpool and a point ahead of Arsenal after 27 league games in tight title race.