I'm pretty sure it's probably just a groin injury lol, watched the replay like 10 times, only thing I could come up with was him stretching to much and pulling his hamstrings or something.
Hopefully not, I don't think it's a bad knee injury (based on my experiences) because he didn't land on his knee awkwardly from a upright position. It could either be a hyperextended knee, or a pulled/torn hamstring/groin. Hamstring tears are notoriously bad in pro sports, they linger all year long. Let's just hope it's nothing serious.