Watford's clash with Chelsea was overshadowed after a supporter collapsed after suffering a cardiac arrest.
During a break in play in the 10th minute while Watford defender Adam Masina needed treatment, players from both sides alerted medical staff from both clubs to the emergency unfolding in the Graham Taylor Stand.
They rushed across the pitch and up to the scene to help paramedics as the area around the male fan was cleared.
Referee David Coote spoke to both benches and captains before taking the teams off the pitch while treatment on the male supporter continued.