Utrecht - Tour de France champion Vincenzo Nibali's under-pressure Astana team requested team-mate Lars Boom be removed from cycling's showpiece race for anomalous blood-testing results announced on Friday.
As excitement built on the eve of the Tour start in Boom's home country, pre-race tests on the Dutch rider in the Kazakh-funded team showed a low cortisol level.
Low cortisol levels can indicate cortisone doping but are not conclusive proof of doping.
Astana is part of the Movement for Credible Cycling (MPCC); a group of teams holding to stricter anti-doping measures than those of cycling's governing body. MPCC rules stipulate that a rider with a low cortisol level should be given a period of rest.
"At 2pm on July 3, Astana Pro Team received analyses from the UCI's independent anti-doping agency CADF from blood tests administered to its nine Tour de France riders on July 2," Astana said in a statement.
"According to the CADF notification, rider Lars Boom has a healthy and permissible level of cortisol for the Tour de France that is however too low for applicable standards from the MPCC."
About one hour after receiving the notification, Astana held a press conference at which Boom was present alongside Nibali. There was no mention of this during the news conference.
Astana then asked the UCI to replace Boom with Alessandro Vanotti, who "will arrive in the Netherlands Saturday morning to undergo physical and blood tests and await a UCI decision on the matter," Nibali's team said.
Astana's request was denied by the UCI, which said the proposed swap came too late.
"As per UCI Regulations, teams can't change their starting list after the sports directors meeting has taken place," the UCI said. "The UCI is committed to apply its regulations consistently and will therefore not authorize any team to change its starting list now."
Because low cortisol levels are not conclusive proof of doping and his levels were within the UCI threshold, Boom can still be allowed to start Saturday's first stage - an individual time trial in the Dutch city of Utrecht - if Astana decides to go against the MPCC recommendations.
The MPCC said he should be rested for "health" reasons.
"In case of abnormally low cortisol levels, competition will resume after an additional 8-day rest minimum, and back-to-normal cortisol levels," the MPCC said.
Astana has been answering many questions of its own in recent months, after five senior and development squad riders were caught doping with EPO and steroids since last August.
Cycling's governing body, UCI, even said there were "compelling grounds" to request that Astana, which is backed by the Kazakhstan government, be stripped of its license altogether.
"Our license was called into question but never taken away," Nibali said at a news conference earlier Friday. "We've paid the price for the riders who doped, but we can't pay the price for mistakes we haven't made ourselves."
Tour de France director Christian Prudhomme could not immediately be reached for comment.