Le Clos stunned the American with victory in the 200 metre butterfly at the London 2012 Games and this week booked a spot in five different events in Brazil after securing required qualifying times at the South African swimming championship.
Whether he features in all of them, though, is unclear.
Le Clos said last year he planned to take on Phelps in the 100m and 200m butterfly and freestyle races at the 5-21 August Games in Rio but has since scrapped the 100m freestyle, failing to enter the event at the national championships in Durban.
His schedule for Rio is the subject of some conjecture with both the swimmer, who turned 24 last week, and coach Graham Hill keeping outsiders guessing.
But he did send out a strong signal to his American rival Phelps, 18-times Olympic champion, with a time of 1 minute 55.04 seconds in the 200m fly and 51.82 seconds in the 100m.
“I'm just happy to get another time under way,” he told reporters after winning the 100m butterfly race.
