VIENNA: Kenyan Eliud Kipchoge's attempt to run an historic but unofficial sub-two hour marathon will take place at 0815 local time (0615 GMT) on Saturday in a bid to attract a bigger crowd, race organisers said on Friday.
The provisional start time had been set at between 0500 and 0900 local time for the world record holder's attempt to break the two-hour barrier.
The sport's governing body, the IAAF, will not recognise the run as an official record because it is not in open competition and it uses in-and-out pacemakers.
"His team are keen that a significant crowd will attend to cheer Kipchoge on and help him make history," the organisers said in a statement.
The weather in Vienna on Saturday is expected to be dry and sunny with a forecast temperature of 9 Celsius at the start, rising to 12 Celsius at the finish.
Kipchoge, 34, who is the reigning Olympic champion and set an official world record of 2:01.39 at the Berlin marathon last September, missed out by 26 seconds when he previously attempted to break the two-hour barrier in Monza in May 2017, without spectators.
Kipchoge's coach Patrick Sang told reporters that he was "100 percent sure" that the presence of the public this time would help the athlete's attempt.
"He believes more in himself," he said, adding that Kipchoge's run in Monza had shown that barriers could be broken.
"If you see the times that have been run since Monza and now in the marathon, so many athletes have run 2:02 hours, 2:03...it's a clear indication we are learning more every day," he said.
Kipchoge will be supported by 41 pacemakers who will run 4.8 kilometre stints and will form a V shape around Kipchoge - as opposed to a Diamond formation in Monza - to try and protect him from the wind.
"More knowledge has gone into the concept of the formation," said Sang.
Kipchoge will run 4.4 laps of a 9.54 kilometre course – consisting of a long straight with a loop at each end – in the Prater park.
(Reporting by Brian Homewood; Editing by Toby Davis)