World champion Tai Woffinden is to take a break of at least a week from speedway because he is suffering from a stress-related illness.
The Great Britain captain had blood tests after suffering dehydration and exhaustion following Wolverhampton's Elite League meeting with Belle Vue.
He has decided to take a break after getting medical advice in Sweden.
"I need time off. No more racing until the World Cup when hopefully I can come back strong," the 23-year-old said.
|Date of birth: 10 August 1990||Born: Scunthorpe|
|2006: Western Australia Under-16 champion||2007: Conference League Riders champion, British Under-18 champion|
|2008: British Under-21 champion, Premier League Riders champion||2013: British champion, Czech Republic Grand Prix winner, world champion|
"I need some time away from it all and I apologise to my fans and to my clubs, but I hope everyone understands."
The Wolves number one became the first Briton since 2000 to be crowned world champion when he won the title in Poland in October 2013.
He is set to lead GB's bid for the World Cup when the competition starts in King's Lynn on Saturday, 26 July when Australia, the United States and Italy will provide the opposition.
Woffinden finished second in the British Grand Prix in Cardiff on Saturday - a result that moved him to the top of the world standings.
He then raced in a rescheduled Polish League meeting 24 hours later, before riding for Wolves in Monday's meeting.
"I'm exhausted and cannot race. I have been struggling to hold onto the bike these last few days since Cardiff," Woffinden said.
"I went to Poland on Sunday and I was shattered. I was leading races but didn't have the physical strength to keep going for four laps and let the lead slip."
Woffinden revealed he had not been eating or sleeping properly because of his hectic schedule.
"When I race in England, I burn 1,500 calories in five rides and that's a fair chunk of daily intake," he said.
"A lot of the guys in my position rely on motorway service stations for food and it's full of sugar and fat - the same in hotels and fast food restaurants. That's a recipe for disaster.
"And my sleep pattern is all over the place so, when you put no sleep together with a lack of proper food, it's not good."
Woffinden will be replaced for Wednesday's Elite League trip to Belle Vue by guest replacement Chris Harris of Coventry.
He will also miss racing in Poland on Sunday, next Monday's Elite League fixture with Lakeside at Monmore Green and a meeting in Sweden the following day.