I don't think there was any doubt, given the way he went down and his response afterward, but now it's official: Iman Shumpert tore his ACL. Here's the first report I've seen, from Adrian Wojnarowski:

New York's Iman Shumpert has suffered a torn ACL in his left knee, league source tells Y! Sports.

Balls. Again, it looked like a ligament tear from the moment Shump's foot hit he ground, but I'd been holding out hope that it looked worse than it actually was, as was the case with Shump's right knee sprain at the beginning of the season. No such luck.

Shump's obviously done for the rest of the series, which sucks, but the bigger concern now is what lies ahead in the coming weeks and months. He'll probably need surgery (Update: Yeap) and he's got months of rehabilitation ahead before he can take the court again. This will affect Shump's availability for Summer League, and might very well continue to be an issue heading into next season. I suppose we'll know more soon enough. It's just a massive, massive bummer, and it feels doubly awful because it's our beloved rook. It was genuinely nauseating to see him in that much pain.

Between Iman and Derrick Rose, this has been a pretty shitty day for basketball and knee ligaments. Speedy recoveries, everyone.

(If you want some slightly promising news for dessert, Jeremy Lin played one-on-one today. We saw some of it during the broadcast.)

Update: Oh, awesome. It's even worse. Alan Hahn:

Update on Iman Shumpert: MRI revealed a torn ACL and lateral meniscus tear. He will undergo surgery in New York and is out 6-8 months

Six to eight months. Fuck.