A prominent football journalist from the United States has died while covering the World Cup in Qatar.
Grant Wahl, 48, collapsed suddenly while watching the Argentina-Netherlands game on Friday night.
Early reports suggest he may have had a heart attack, but this has yet to be officially confirmed.
Last month Mr Wahl was briefly detained by Qatari authorities for trying to enter a stadium wearing a rainbow shirt, in support of LGBT rights.
In a statement, the US Soccer Federation said it was "heartbroken" by the news.
"Fans of soccer and journalism of the highest quality knew we could always count on Grant to deliver insightful and entertaining stories about our game, and its major protagonists," it said.
In a tweet, Mr Wahl's wife, Céline Gounder, said she was in "complete shock", adding that she was "so thankful" for the support she had received from friends.
FIFA President Gianni Infantino said Mr Wahl's love for football was "immense", adding that his reporting would be "missed by all who follow the global game".
A spokesperson for the Qatari body responsible for planning the World Cup, the Supreme Committee for Delivery & Legacy, said: "We are deeply saddened by the death of the US journalist Grant Wahl.
"Grant was known for his enormous love of football and was in Qatar to cover his eighth Fifa World Cup.
"He fell ill in the Lusail Stadium media tribune, during last night's quarter-final match between Argentina v Netherlands. He received immediate emergency medical treatment on site, which continued as he was transferred by ambulance to Hamad General Hospital.
"We are in touch with the US Embassy and relevant local authorities to ensure the process of repatriating the body is in accordance with the family's wishes."
Mr Wahl reported on eight consecutive World Cups, with his first in the US in 1994.