According to www.metro.co.uk, De Bruyne faces around two months out after suffering the injury when he caught his studs in the turf before leaving the training ground on crutches.
De Bruyne and his City teammates attended the premiere of a documentary series about the team hours after the midfielder injured his right knee in a training session.
The 27-year-old was one of the Blues' most influential players during their record-breaking 2017-18 campaign.
Sam Lee from Goal has since reported that the Belgian worldwide is already on crutches from the training ground and will be assessed in both Manchester and Barcelona.
But the importance of De Bruyne, easily the club's best player in the record-breaking 2017/18 season, can not be overstated.
City became the first team ever to win 14 successive English top-flight games when they triumphed 2-1 at Old Trafford last December.
Any significant lay-off would come as a serious blow to City's hopes of successfully defending the Premier League title.
India vs England 3rd Test, Day 1
Succeed, and he does not merely make runs; he protects India's middle order from the new ball, and sets the team up to thrive. On the other hand, the England team are looking in great form with every member contributing in the victory.
I would have left Chelsea had Conte stayed - Willian
Sarri insisted that the 31-year old has a long life at Stamford Bridge as he is very compatible and complete defender. Do you really want me to tell you?" Yes, because we play different football now, with a different playing style.
Neil Warnock: 'Criticism of Newcastle United owner Mike Ashley is hot air'
West Ham United and Bournemouth are entering their head-to-head contests with completely different results from Matchweek 1. Both of these sides scored and conceded last weekend, a trend that looks set to continue on Saturday afternoon.
He was maybe the main man for us last season.
City have spent big in an effort to bridge the gap on their fiercest rivals, with the "noisy neighbours" seeking to take control in Manchester and of domestic competition in England.
Raheem Sterling and Bernando Silva scored to secure a comfortable victory. They have given me a fantastic squad.
"Every season is a major season and this game was complicated but we played at a high level".
"We are used to getting a lot of camera attention but mostly on the pitch". We keep going. We are satisfied for many, many reasons.
For the first time this year, City's title odds have lengthened as Liverpool's are cut.