"I'm so proud of having won Olympic gold in the 10,000m," said Cheptegei, who won silver in the event in the Tokyo Games.
"So proud for Uganda. After the world junior 10,000m title, three times the world 10,000m titles, the world 10,000m record, this gold medal in an Olympic record time completes my collection.
"After discussing with my team, we've decided it's best not to compete in the 5,000m."
Heats for the 5,000m are scheduled for Wednesday, with the final slated for Saturday.
