Lenin Castillo is responsive but has been rushed to hospital after being knocked out by Callum Smith on the undercard of Anthony Joshua's world heavyweight title fight against Oleksandr Usyk.
An overhand right from the Liverpudlian midway through the second round caught Castillo (now 21-4-1, 16KOs) flush on the temple, leading referee Bob Williams to immediately halt the contest after the Dominican had hit the canvas.
Smith (28-1, 20KOs) jumped on the rope but cut short his celebrations in concern for his stricken foe, whose legs appeared to be trembling as paramedics swiftly entered the ring at Tottenham Hotspur Stadium.