Castles reports that Marcus Rojo might not play again until September after he tore his ACL in the first half.
The English Premier League club announced on Saturday that Ibrahimovic sustained "significant knee ligament damage" on Thursday in the Europa League quarterfinal victory over Anderlecht.
Manchester United striker Zlatan Ibrahimovic and defender Marcos Rojo are likely to miss the rest of the season after scans revealed they have both suffered cruciate knee ligament injuries.
While the Portuguese is confident he has "options" up front, with Wayne Rooney ready to return, on the defensive front he is already without long-term absentees Phil Jones and Chris Smalling.
"We are in trouble", said manager Jose Mourinho. "In this moment, Eric Bailly has played six matches in a row, and we have lost Rojo, we don't have Jones or Smalling, we are in trouble and now we lose Zlatan too".
Although he limped away after the match, it was clear that Ibrahimovic's injury was more than just a small setback.
Ibrahimovic landed awkwardly when challenging for the ball and as a result may have played his last game for the club, as his contract expires in the summer.
Liverpool fans believes that Ibrahimovic's injury blow will help their cause to finish inside the top-four places, with United now chasing them down.
Manchester United fans were quick to express their support towards Zlatan on social media.
Furthermore, they were drawn against Celta Vigo in the semi-finals of the Europa League on Friday afternoon.
The 35-year-old Ibrahimovic is United's top scorer this season with 28 goals in all competitions while Rojo has established himself at the heart of the defence.