Watford defender Christian Kabasele was taken to hospital after being forced off against Chelsea having suffered a nasty collision with the post.
Chelsea started brightly and after goalkeeper Ben Foster was rounded, Kabasele slid towards goal attempting to preserve the clean sheet - only to suffer a horror injury.
He hit the post under his right arm as fans and Watford coaching staff were left concerned while medical staff attended to him before he was helped off the pitch to be replaced by Adrian Mariappa.