Chelsea’s Levi Colwill faces an extended period on the sidelines after undergoing surgery to repair an anterior cruciate ligament injury. The 22-year-old England international suffered the serious knee damage during the club’s initial pre-season training session on Monday, mere weeks after their Club World Cup victory.Reuters | Levi Colwill has suffered an ACL injury on Chelsea’s first day back in trainingMedical scans conducted on Wednesday evening confirmed the severity of the injury, with the operation taking place on Thursday.The setback occurred in the closing moments of Chelsea’s first training session following their brief three-week break after the Club World Cup final on 13 July.Speaking at a press conference on Thursday before the surgery was confirmed, Maresca acknowledged the severity of the situation.”We had a problem the last two days with Levi Colwill, that we don’t know how long he is going to be out,” the Italian manager stated.”So for us, we will see, hopefully not too long, but for sure it’s a problem for us.” At that point, the specific nature of the injury remained unclear.”We need to wait, we don’t know yet [what the specific injury is]. It was in the first session on Monday, just in the last minutes of the session. He felt something and, as I said, we need to wait and then we see,” Maresca explained before the news broke.The injury represents a cruel twist for Colwill, who played a crucial role in Chelsea’s successful campaign last season.The defender scored the vital goal against Nottingham Forest on the final day to secure Champions League qualification for the Blues.Reuters | Levi Colwill’s injury is a huge blow to ChelseaMaresca emphasised the player’s significance to the team’s achievements. “I spoke with him yesterday and I told him that if we achieve what we achieved last year, it is also because of him – and he was a main player for us,” the manager revealed.Chelsea’s players had minimal recovery time between their Club World Cup triumph and the resumption of training, with just three weeks separating the two.With the transfer window closing on 1 September, Chelsea must now evaluate their defensive options. The club recently acquired teenage defender Jorrel Hato from Ajax, who offers versatility across centre-back and left-back positions.LATEST SPORT NEWS:Reuters | Enzo Maresca must now ponder whether to enter the transfer market for a replacementCurrent central defensive alternatives include Trevoh Chalobah, Renato Veiga, Tosin Adarabioyo and Benoit Badiashile. However, Axel Disasi currently trains separately from the main squad.Maresca indicated the club might pursue additional reinforcements, stating: “It depends. We need to wait and then we see. But, as I said, we know each other from last year and, you know in our way, how important Levi has been.”The Conference League and Club World Cup winners face Bayer Leverkusen in a friendly on Friday.