Three minutes or six? The World Cup's heat-break fight, as Japan heads into a Monterrey night

Tunisia were already cooling down in Monterrey

On June 15, Tunisia's players trained at a Monterrey facility with extra hydration stations and cooling gear, as HNGN reported. Monterrey is where Japan meets Tunisia on Saturday night, local time.

The heat shaped the rules before a ball was kicked. For the first time, FIFA has made a three-minute hydration break mandatory midway through each half of every match, regardless of temperature or whether the roof is closed, the Associated Press reported via NBC. FIFA said the aim was to "ensure equal conditions for all teams," drawing on last summer's Club World Cup, where temperatures climbed into the mid-30s C.

The dispute is over the number itself

In May, a group of sports scientists wrote to FIFA arguing three minutes is not enough, asking for breaks of at least six minutes and stricter thresholds. Among the signatories was Yuri Hosokawa, associate professor at Waseda University's Faculty of Sport Sciences, alongside Douglas Casa of UConn's Korey Stringer Institute. Casa's point is arithmetic: aggressive cooling lowers body temperature by only about 0.12 C per minute, so the length of the break dictates how much it can actually do. Hosokawa has warned that once core temperature passes 40.5 C, players can grow confused or lose consciousness — signs of exertional heat stroke.

The criticism cuts the other way too. Some coaches and commentators say the breaks are unnecessary in cool conditions and merely interrupt the flow, handing managers a free chance to shift momentum. Others have noted the hundreds of new commercial slots the breaks create. Player welfare and broadcast money are pulling on the same three minutes.

What it means for Japan's Saturday

Research cited by climate and sports-medicine experts suggests roughly a quarter of World Cup matches could face dangerous heat, with afternoon kickoffs in Dallas, Houston, Miami and Monterrey carrying the highest risk. FIFPRO recommends matches be postponed once wet-bulb globe temperature climbs above about 28 C, Al Jazeera reported.

Japan's draw is one of the cooler slots by design. Tunisia vs Japan kicks off at 21:00 local in Monterrey on June 20 (04:00 GMT June 21), per Goal — an evening start, not the punishing afternoon. But Monterrey's humidity keeps the wet-bulb reading high after dark, which is exactly the variable the breaks are meant to manage. Heat is not the only surface complaint, either: France's Adrien Rabiot and Brazil's Vinicius Jr. have criticized pitches in the New York-New Jersey area.

The match itself is a marker — the 1,000th in men's World Cup history. Whether an extra cooling break is added on Saturday depends on the WBGT reading at kickoff, and that number is not known yet.