Reigning world champion Philippe Gilbert of Belgium and American rider Taylor Phinney have both been ruled out of Sunday's Tour of Flanders, their team BMC announced on Thursday.
Gilbert, who has twice finished third in the spring classic race, is currently recovering from a cold and is not in suitable condition to take part, while Phinney has a knee injury and is hoping to return to peak condition for the Paris-Roubaix on April 7.
"With my current condition, I know I cannot be successful at Flanders," Gilbert was quoted as saying on BMC's official website.
Phinney said: "I'm confident if I stay at home in Italy and have a couple more days of recovery, I can be back 100 percent for Paris-Roubaix."
Britain's Adam Blythe has been named in the BMC team for the race to help cover for the duo's absence.