The American rider is being taken care of at the Maurizio Bufalini Hospital in Cesena but the medic's report isn't that good.
"The clinical picture remains extremely serious and compared to the previous day there have been no changes".
Hayden, who was in Italy following a race at nearby Imola, was transported to a local hospital following the incident on the Rimini coast, before being transferred to Cesena.
Since the accident, Hayden's girlfriend Jackie and several members of the Honda World Superbike team that he now races for have been with him too.More news: Windows 10 update aims to help identify best photos, videos
Former MotoGP world champion Nicky Hayden is in a "extremely critical" condition in intensive care after a cycling accident in Italy.
From the past season, he returned to the Superbike Championship with the Red Bull World Superbike Honda, replacing Sylvain Guintoli alongside Michel van der Mark.
American motorcycle racer Nickey Hayden sustained multiple injuries in a cycling accident in Italy.
Hayden's fiancee Jackie and team members were joined at his bedside by brother Tommy and mother Rose who flew in from the United States.More news: Trump Says New FBI Director Could Be Named Next Week
"After a few years we fought for the title down to the last race in Valencia and, unfortunately for me, he won and became MotoGP world champion".
In 2016, he returned to the Superbike World Championship with the Ten Kate Racing-run Honda squad, now known as the Red Bull Honda World Superbike Team. He competed in Moto GP from 2003-2015. He further said "Come on Nicky, we're all with you".
Britain's Tour de France champion Chris Froome escaped unhurt this month while having his bike written off in a hit-and-run incident near his Monaco home.More news: Erdogan visits Trump, amid much friction between US, Turkey