British cycling performance director Sir Dave Brailsford has urged caution over Plymouth cyclist Jonathan Tiernan-Locke's blood investigation.
Tiernan-Locke hit the headlines on Sunday when it was revealed that he had been asked by the International Cycling Union (UCI) to explain possible discrepancies in his biological passport.
The 28-year-old Team Sky rider has withdrawn from racing while his response to the UCI is prepared.
Although Tiernan-Locke has not yet made a statement, family and friends have rallied around to support him.
His twin sister Caroline took to Twitter and said: "Please wait for the explanation before jumping to conclusions.
"He is an honest, hard-working, innocent rider. There is nothing but pure talent and sheer determination behind that boy."
Close friend Simon Aske runs Paignton's Colin Lewis Cycles shop, where Locke worked during his early days as a part-time professional. He said: "I am more than 100 per cent certain that Jon is clean, and it disgusts me about some of the people out there even questioning him."
Brailsford, who is also Team Sky's general manager, has said it was "absolutely" possible there could be an innocent explanation for any discrepancy. He added: "He hasn't failed anything yet or there's nothing where you would say absolutely categorically: 'This is something which needs to be addressed'.
"It appears there is an anomaly which needs to be looked at and explained," he said. "This isn't the first time that this has occurred.
"We've got to allow them to carry on with the process, get both sides of their roles done, try to establish the truth – which is the important thing.
"Once we have the truth, we can all deal with that and go from there."
The discrepancies in his biological passport are believed to relate to Tiernan-Locke's time with Endura Racing. He was riding for them when he won the Tour of Britain in 2012.
Endura's general manager, Brian Smith, told Cycling News website: "I can put my hand up and say 100 per cent that I don't think he was doping at Endura Racing. There was no suspicion, no nothing."
Tiernan-Locke, who has struggled with form since his move to Team Sky, has had problems with ill heath, and spent two years out of the sport due to a glandular problem and chronic fatigue syndrome.
Smith added: "I can only think it's hormonal or a gland problem like he has had in the past. The training at Sky, I think, has pushed him over the edge.
"His body cannot take the same training as Bradley Wiggins and Chris Froome. It has run him down and then his hormones have gone into overdrive."