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.
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