Tait won the Kentucky event in 2000 aboard Welton Envy and competes this year on Xanthus III.
He last competed at the Olympics in Athens in 2004 and then came out of retirement to try to qualify for the 2012 London Games.
Blyth Tait and Xanthus III Photo: Photosport
Tait failed to qualify for London, but at 54 he's still hopeful of making the four strong Rio equestrian team.
"If I had another 12 months up my sleeve I would be more confident but obviously we will know more at the end of the weekend as to whether Rio is a realistic goal or not... but I think whatever happens this weekend we are still all in the mix based on the development and results we've achieved at this point," Tait said.
There are four spots up for grabs for Rio with Tim Price, Sir Mark Todd, Jonelle Price and Jonathan Paget all in contention.
The Kentucky had changed little in the time he has been away and Tait believed it would suit him.
"This horse (Xanthus III) is a very bold horse and a good galloping horse and the course tends to suit that kind of horse. He's travelled over well and been working well so we will give it our best shot."