So says medical expert Ben Dinnery, who runs the Premier Injuries site and has a background in sports science and data analysis.
The meeting between Newcastle United and Spurs on 17 October, which the away team ultimately won 3-2, was halted midway through the first half.
Reguilon alerted the referee that a fan had collapsed in the stands while Dier demanded a defibrillator be rushed onto the scene.
The supporter, who it later emerged had gone into cardiac arrest, was then stabilised by on-site medics.
As reported by the Evening Standard the following on 19 October, he is now in a non-critical condition.
Dinnery saluted Reguilon, Dier and everyone else involved in the resuscitation effort.
“It cannot be understated that time is of the essence,” he told Football Insider correspondent Adam Williams.
“When someone goes into cardiac arrest, we’re talking about a lack of blood flow, lack of oxygen travelling to the brain and the heart.
“The longer that goes on, the more damage that happens to the cells in those areas. That can lead to complications.
“We know that bystander CPR increases the survival rate and minimises the risk of long-term damage greatly. That’s massive.
“The quick defibrillation was key as well. Initially, it was given by the St John Ambulance department and then by Newcastle club doctor Paul Catterson.
“Without that rapid response, the outcome could have been massively different. So big credit to the players who alerted the right people.
“If you are going to have a heart attack, there is probably no better place than a football match.”