Mark Cavendish (Etixx-QuickStep) suffered an illness while attending the Cape Town Cycle Tour in South Africa last week, placing doubts on his form going into this week’s Tirreno-Adriatico, and Milan-San Remo on March 22.

Cavendish took the long trip to South Africa to take part in the Cape Town race on Sunday, March 8 with team-mate Mark Renshaw. Renshaw placed fourth behind defending champion Nolan Hoffman (Team Abantu) in a race shortened due to recent forest fires in the area.

“Just landed in Europe after 5 days in South Africa for @CTCycleTour representing @KleinConstantia. Got a virus, but saw a beautiful place!” the Manx sprinter said via his Twitter account on Monday morning.

Cavendish did not elaborate on the nature of his illness, but must now get ready for Tirreno-Adriatico’s start on Wednesday. Last year, Cavendish took the overall lead after his Omega Pharma-QuickStep squad won the opening team time trial. Cavendish went on to win stage six of the race.

So far this season, Cavendish has won more races than any other rider. His tally of six victories has come from a stage of the Tour de San Luis, two stages and the overall at the Dubai Tour, the Clásica de Almería and Kuurne-Brussels-Kuurne.

Cavendish will use Tirreno to hone his form ahead of this year’s Milan-San Remo, where he is looking to repeat his victory from 2009 in the prestigious monument. Only time will tell whether the virus picked up in South Africa will have a lingering effect as the month progresses, and whether his trip to the country was a risk not worth taking at this vital part of the season.

Cavendish’s sprint rival Marcel Kittel (Giant-Alpecin) will not take part in Tirreno due to a virus. British overall contender Chris Froome (Sky) announced on Monday that he, too, was suffering from illness. Froome took the decision to withdraw from the start list of Tirreno to focus on recovery.