After setting up Manchester City's third goal at Swansea, Kevin De Bruyne limped out of the game with a hamstring injury and was replaced by Jesus Navas nine minutes from time.
The 25-year-old attacking midfielder was assessed by the club's doctor on Sunday and it has now emerged that he face around four weeks on the sidelines.
According to sources close to the player, initial scans have revealed a muscle tear and the Belgian international is now expected to travel to Barcelona for further tests and treatment.
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De Bruyne has made an outstanding start to the new Premier League campaign, starting all six games and scoring twice in addition to providing four assists.
The Belgian's top-class ability to influence his team's style of play was highlighted by his man-of-the-match performance against Manchester United in the derby win at Old Trafford.
Which games will he miss?
As a result of his injury, the gifted playmaker won't be available for City's Champions League tie at Celtic on Wednesday or their trip to Tottenham on Sunday - but that's not all.
De Bruyne is also set to miss league games against Everton and Southampton, but most significantly, he is also likely to play no part when Pep Guardiola's side go to the Nou Camp on October 19 and when they return to Old Trafford in the EFL Cup Round of 16 seven days later.
While the international break will lessen the impact of his injury on his club, Man City fans and even supporters of City's upcoming opponents are well aware of the importance of his absence.
As you can see below, they have taken to Twitter to react to the news that one of the stand-out stars of the season so far is now preparing for an extended period out of action:
Guardiola on De Bruyne
Following his team's 3-1 win at the Liberty Stadium, Guardiola said he didn't know how bad the injury was but hoped that it wasn't too serious.
"It looks like it was muscular, but I am not a doctor," he said. "It is a pity because he (De Bruyne) is an important player. (But) that's why we have to have a big squad as everyone will help us."
How much will City miss De Bruyne? Leave YOUR opinion in the comments box below!