Monaco's royal palace says the wedding festivities, originally scheduled for July 8 and 9 of next year, will now take place on July 2 and 3.
In a statement Sunday, the palace said the charge was made to accommodate a July 5-9 meeting in Durban, South Africa by the International Olympic Committee.
The palace says "the couple wished for the presence of the Olympic family by their sides."
Alfred met Wittstock during a 2000 swimming competition in Monaco and they have been seen regularly together in public since 2006. The couple announced their engagement in June.