Bahrain Victorious lost their main contender for the Vuelta a España when Antonio Tiberi - in fourth place overall - dropped out of the race on Sunday.
Tiberi was five minutes down on race leader Ben O'Connor but was having one of the best Grand Tour seasons of his young career, having finished fifth overall in the Giro d'Italia and in line for another top 10 in the Vuelta.
However, his good form was turned upside down by temperatures that soared over 37°C (100°F). His team stated Tiberi had been "suffering from heat stroke, becoming lightheaded with a high body temperature".
Heat exhaustion and heat stroke can have overlapping symptoms. Heat exhaustion occurs when the body loses too much water and electrolytes from sweating and can result in weakness, fatigue, high heart rate and lightheadedness. Heat stroke can occur when overheating raises the body's temperature above 40°C (104°F) and can be life threatening.
Tiberi had been in the jersey of best young rider for stages 4, 5, 7 and 8 but when he abandoned on Sunday's stage 9, it passed to Florian Lipowitz (Red Bull-Bora-Hansgrohe).
"This Vuelta was going really well from the beginning until two days ago," Tiberi said. "The legs were really good and especially after the Giro, having these feelings was super nice for me.
"[Wearing] the white jersey was a really good moment, I was in a really good shape, and the legs were super good," Tiberi said.
"But yesterday, with this super hard stage from the beginning and especially in the heat, I suffered a lot with overheating. I tried to cool down the body with water and ice but it was not enough. The body said stop, the mind wanted to keep going but the body stopped and I couldn't do anything."
Tiberi said the team tested him for COVID-19 but he dismissed the concerns.
"Already today I feel normal and feel well. Yesterday was just a bad day."