Belgian cyclist Michael Goolaerts has died aged 23 after a crash in Paris-Roubaix.
The Veranda's Willems-Crelan rider fell on the second set of cobbles in the one-day classic in northern France.
He suffered cardiac arrest and was airlifted to hospital in Lille but died at 21:40 BST on Sunday.
"It is with unimaginable sadness that we have to communicate the passing of our rider and friend Michael Goolaerts," read a team statement.
The team said Goolaerts died "in the presence of his family members and loved ones, who we keep in our thoughts".
The statement added: "For now there will be no further communication as we want to give his close ones time to deal with this terrible loss."
Goolaerts crashed 109km into the 257km race and was found unconscious by race doctors. Television footage appeared to show him receiving CPR treatment from medics at the side of the road.
David Lappartient, president of cycling's world governing body the UCI, said: "On behalf of the UCI and the cycling family as a whole, I would like to extend my deepest condolences to the family, team and loved ones of Michael Goolaerts, who left too early.
"We share their immense sadness."
Goolaerts was in his fourth season - in two spells - with Belgian outfit Veranda's Willems-Crelan.
He spent 2013 and 2014 with them at the continental level, and returned in 2017 after a season as a trainee with Belgian World Tour team Lotto-Soudal, when he won the opening stage of the 2016 Tour du Loir-et-Cher on the UCI Europe Tour.
He rode several of the cobbled classics and semi-classics this season, finishing ninth at Dwars door West-Vlaanderen and 20th at both Kuurne-Brussels-Kuurne and Driedaagse De Panne.
Goolaerts was riding his first senior Paris-Roubaix, having competed in the under-23 edition in 2015.
Paris-Roubaix, which is known as the 'Hell of the North', is regarded as one of the toughest races in cycling, featuring 29 cobbled sections.
It is one of the five 'monuments', the most prestigious one-day races.
World champion Peter Sagan won the 2018 edition in a sprint finish with Silvan Dillier.
Tributes from the cycling world
Team Sky: "Everyone at Team Sky is heartbroken by the loss of Michael Goolaerts. Our thoughts are with his family, friends, and all at Veranda's Willems-Crelan."
Team Lotto-Soudal: "Devastating news. Our most sincere condolences to the family, friends and team of Michael Goolaerts."
Three-time Paris-Roubaix winner Fabian Cancellara: "Terrible news. RIP Michael Goolaerts. My deep condolences go to his family, friends, team-mate and the Veranda's Willems-Crelan crew."
Two-time Tour de France winner Alberto Contador: "My deepest sympathy to the family and friends of Michael Goolaerts, since the end of the race I have not stopped thinking about him."
Paris-Roubaix 2018 winner Peter Sagan: "All the thoughts and prayers of the Bora-Hansgrohe team and myself are with Michael Goolaerts. Such a sad news."
Quick-Step Floors: "Our thoughts go to the family, friends and team of Michael Goolaerts in these unimaginable moments of sadness. May he rest in peace."