The duo, hoping to upset sprint king Usain Bolt at the Olympics later this month, will meet in the Diamond League meeting at Crystal Palace on July 13
"I'm looking forward to taking on Tyson," the 29-year-old Powell said. "It's good to have him back ... it's going to make for a very competitive Olympic Games.
"Hopefully the world will be able to see the four fastest men ever ... in the 100 final in August in London - what a race that would be."
Gay, who has clocked the world's second fastest time behind Bolt, said he was peaking at the right time after battling against injuries.
"My body is getting closer to where I want it to be," Gay said. "I've shown over the years that through all of the injuries I'm a fighter and I hope to be fighting for that Olympic gold in London."
Last week Powell and Gay secured their places at the Games by clocking 9.88 and 9.86 seconds respectively at their national trials.