After all the rumors yesterday, Chelsea confirmed earlier today that Christopher Nkunku did indeed suffer a serious knee injury, and that he has in fact undergone an operation for it.
Chelsea did neglect to provide any more specific details beyond that, so we still don't know what the actual problem was, nor did they provide an expected timeline of recovery — just that he would be out for an "extended period". How very helpful.
Reports, such as from The Athletic, expect a four-month recovery, which does point to a ligament issue, like an MCL (but not the ACL, which tends to need around 6-9 months). Rumors yesterday were guessing MCL or meniscus, but perhaps both in this case (hard to avoid meniscus problems in any sort of knee injury).
In any case, with Nkunku out for the first half of the season, our prospects of making a good start to the season look a bit dimmer. We'll see if this prompts Chelsea to dip back into the transfer market, as with Wesley Fofana's ACL injury.
Get well soon, Christo!