The INEOS 1:59 Challenge will start at 9:19am East African Time, Organisers confirmed on Friday.
Kenya's Eliud Kipchoge will be attempting to become the first athlete to go below two hours in a marathon in his INEOS 1:59 Challenge in Vienna on Saturday.
"The #INEOS159 Challenge will begin at 08:15 CEST tomorrow morning. But where in the world will you be watching?" read a tweet from the INEOS 1:59 Challenge organisers on Friday afternoon.
Kipchoge holds the men's marathon world record with a time of 2hr 01min 39sec, which he set in Berlin on September 16, 2018.
The 34-year-old Kenyan will attempt in Vienna in a huge park where the path has been specially prepared for this event to become the first athlete to run the distance below two hours. Two years ago he tried, and failed by 26 seconds, at Monza, Italy.