Nixon, one of the last players to complete the first round, was the ninth person to eagle the par-5, eighth hole Thursday. He finished with an 8-under-par 64.
The strong close allowed Nixon to leapfrog past Marco Crespi and Jbe Kruger for the outright lead. Crespi and Kruger each had four-birdie strings -- over Nos. 12-15 -- in posting scores of 7-under 65.
Christiaan Basson and Retief Goosen are tied for fourth at 5-under.
Nixon started on the second nine of the Glendower Golf Club, posting birdies in the first three holes. He added others at the back-nine par-3s -- 14 and 17 -- to make the turn at 5-under.
His lone bogey came at the par-5 second hole. He was one of only 17 players to bogey that hole Thursday. He got the stroke back at No. 3 -- another par 3. A 16th-hole birdie got him within one of the leaders and the eagle at the par-5, 477-yard eighth put him ahead.
Crespi and Kruger, in addition the four consecutive birdies, each had six birdies, one bogey and an eagle Thursday. Crespi had the day's only eagle at the 444-yard, par-4 seventh hole and Kruger was among those with an eagle at No. 8.