He was on the ground injured as play developed for his second goal. He saw that play was continuing and got up gingerly and sort of stumbled with the ball over the line. Subbed soon after, probably as precaution but can't be sure.
If it's one of them, Palace or boro to go down with Swansea and Hull I'm going to enjoy watching it unfold. Ideally it'll be Sunderland to drop though.