Extra ice and water trucks have been ordered and water-spraying archways and sprinklers have been installed for the competing horses.
While temperatures for Saturday are tipped to reach 34 degrees - a temperature still considered comfortable for both horses and riders in dry heat - the decision to alter the course was made in the event that temperatures climbed even higher.
"This is still an exciting and challenging course being tackled by some of horse riding's biggest stars," Chair Bob Gillen says.
"Instead of taking about 11 minutes to complete the course, it will now take about eight minutes and there are some terrific vantage points both in Rymill Park and other sections of the parklands where shade is plentiful."
The decision - which impacts on all event classes - was made this morning at a meeting of organisers and officials, including veterinarians and members of equestrian's world body, the FEI.
The course still meets all FEI regulations and acts as a qualifier for world championships, including the 2012 Olympics. The decision was based on data collected at both the Atlanta and Beijing Olympics where horses had to face humidity as well as heat, considered more difficult to deal with than Adelaide's dry temperatures which allow horses to sweat and then cool.
The Australian International 3 Day Event - the Southern Hemisphere's most important equestrian event - is expected to attract up to 30,000 people with dressage beginning this Friday.
Olympic gold medallists Wendy Schaeffer and Stuart Tinney will battle it out against some of the biggest names in the equestrian world including silver medallists Shane Rose, Megan Jones and Sonja Johnson and defending champion in the Olympic level four star class, Christopher Burton. More than 110 riders have entered the event, up from 80 riders who competed last year.
The event will also play host to New Zealand's finest horse and rider combinations competing against the Aussies for the hotly contested Adelaide Trans Tasman Challenge, which was won by the Kiwis in New Zealand in 2007.
With the Saturday of the event coinciding with the running of the Credit Union Christmas Pageant on 14 November, organisers are theming the day as a "family day" encouraging families to enjoy the fabulous sights and sounds of the Pageant and then spend the afternoon relaxing in the parklands.
Spectacular showjumping, a challenging cross country course and tests of elegance and precision in the dressage arena are features of the Adelaide event, one of only six four-star events in the world.