Sam Willoughby's surgery has soured a dream weekend for Australian cycling as it emerges from the wreckage of the disastrous Rio Olympics campaign.
Caleb Ewan won the last stage of the Tour of Britain, where Rohan Dennis was second overall.
The Australian Orica-BikeExchange team ended an outstanding Vuelta a Espana (Tour of Spain) with Magnus Cort Nielsen taking out the last stage and Estaban Chavez again confirming his Grand Tour potential with third overall.
Chavez also was second overall earlier this year at the Giro d'Italia.
BMX star Caroline Buchanan returned to mountain biking and won her seventh world title, while Katrin Garfoot became the first Australian to take out the Chrono Champenois time trial in France.
But Willoughby had to undergo surgery on his back and neck after a BMX training crash.
The accident happened on the weekend at his home track in Chula Vista, near San Diego.
The 2012 BMX Olympic silver medallist was airlifted to hospital and underwent scans on his back and neck after Sunday's crash.
It is believed he landed heavily on his back.
Immediate reports suggested the 25-year-old was conscious and able to move his arms when assessed at the scene.
Willoughby's parents have flown to the US to be by his side, and News Corp Australia reports his mother, Susan, spoke to him over the telephone before the surgery.
Willoughby, a world champion in 2012, finished sixth in the final at the Rio Olympics.
The Australian cycling team went to Rio with reasonable expectations of at least two or three gold medals, but could only manage a silver and a bronze.
Cycling Australia has promised a comprehensive review after the team performed below expectations for the third-straight Olympics.
Buchanan failed to make the women's BMX finals after qualifying second-fastest.
She also finished below expectations in London and the Rio result left her devastated.
Last week Buchanan and partner Barry Nobles became engaged and on the weekend she won the four-cross world championship.
It is Buchanan's fourth mountain bike world title.
Dennis was on target for silver in the Olympics road time trial when one of his aerobars broke, forcing a bike change, and he finished fifth.
Garfoot similarly was a strong medal chance in the women's time trial, but she fell ill a few weeks before the Olympics and finished ninth.