As noted, WWE is reporting that Seth Rollins re-injured his right knee during the closing segment of this past Monday's RAW during Samoa Joe's attack. It was noted that Rollins will be evaluated later this week.
While not confirmed, Rollins did appear to fall awkwardly when being taken down by Joe in the Coquina Clutch, as seen in the video above at the 3:20 mark.
Rollins was forced to miss 6 months of action after tearing the ACL, MCL, and medial meniscus in his knee during a match with Kane at a WWE live event in November of 2015. The then-WWE World Heavyweight Champion was forced to vacate his title, and missed last year's WrestleMania 32 pay-per-view.