Marcel Kittel was listed as one of the headline riders for the Tour of Britain but his Katusha-Alpecin team announced on Wednesday that he would not take to the start line.
Kittel - who was eliminated from the Tour de France for missing the time cut alongside Mark Cavendish on stage 11 - abandoned the BinckBank Tour earlier this month and then the Deutschland Tour last week after racing just the first stage.
In a statement, he said: "Unfortunately for precautionary reasons, I won’t start in the Tour of Britain on Sunday. In my current situation, it makes no sense to race."
Ahead of the race, which starts in Wales on Sunday, he said: "I have to wait for the results of further examinations. The risk would be too high."
Kittel raced the event in 2014, winning two stages, and also competed in the Tour de France that year, when the Grand Départ toured Leeds, Harrogate, York, Sheffield, Cambridge and London.
Over the course of the 2014 Tour, he won four stages, including those ending in Harrogate and London.
"The Tour of Britain would have been one of my highlights in the second half of the season. I have wonderful memories of 2014: not only my two stage wins in the Grand Départ of the Tour de France but also the double stage win in the Tour of Britain are well remembered," he said.
"The British are an enthusiastic and competent cycling community. It’s a pity not to be able to stand at the start line."
Kittel's illness is still unknown, but he said after leaving the BinckBank Tour: "I didn't feel good and well recovered and I need to get a full health check now to know what is going on."
The Katusha-Alpecin line-up for the 2018 edition of the race now includes Alex Dowsett, Tony Martin, Nils Politt, Mads Würtz Schmidt, Dmitry Strakhov and Rick Zabel.
Michelle Arthurs-Brennan is Cycling Weekly's Tech Editor, and is responsible for managing the tech news and reviews both on the website and in Cycling Weekly magazine.
A traditional journalist by trade, Arthurs-Brennan began her career working for a local newspaper, before spending a few years at Evans Cycles, then combining writing and her love of bicycles first at Total Women's Cycling and then Cycling Weekly.
When not typing up reviews, news, and interviews Arthurs-Brennan is a road racer who also enjoys track riding and the occasional time trial, though dabbles in off-road riding too (either on a mountain bike, or a 'gravel bike'). She is passionate about supporting grassroots women's racing and founded the women's road race team 190rt.
She rides bikes of all kinds, but favourites include a custom carbon Werking road bike as well as the Specialized Tarmac SL6.
Best road bike helmets for every kind of rider
How do you maximise safety and comfort? Balance aero and weight? Work out how to find your perfect lid with our helpful buyer's guide
By Hannah Bussey •
Annemiek van Vleuten already cycling again after suffering broken bones at Paris-Roubaix
The Olympic time trial champion managed to start riding just ten days after she broke her shoulder and pelvis in two places at Paris-Roubaix
By Ryan Dabbs •