South African duo Martin Maritz and Tyrone Mordt each shot a bogey-free 9-under 62 and shared the first-round lead at the Joburg Open on Thursday.

Both players had nine birdies to top the leaderboard by one shot at the $1.7 million event, the last — and richest — of the four tournaments in South Africa to open the European Tour's 2011 Race to Dubai.

Another South African, Branden Grace, was one shot back after getting six birdies and an eagle for a 63. Thomas Aiken and Frenchman Alexandre Kaleka were tied for fourth at 7 under.

Maritz's faultless performance on the longer, tougher East Course at Royal Johannesburg was the round of the day.

The 33-year-old Maritz, who gave up full-time tour golf three years ago to become a club pro in the United States, picked up shots at his first two holes and then had four consecutive birdies starting with No. 13 to top the leaderboard alongside Mordt — who opened on the shorter West Course.

Players alternate courses over the first two days at the Joburg Open, which was co-sanctioned by the Sunshine Tour, with the final two rounds played on the championship East Course. Both courses are par-71s.

Maritz hit his approach to 3 feet for a tap-in birdie on the first, and then put his tee shot within 5 inches on the short par-3 second. He ended with a birdie four on 18.

"I'm ecstatic, it's a magical round for me, I'm over the moon," 6-foot-5 Maritz said. "I took a little break over the last three years. It was a great experience but I just missed the game and thought I had to give it one more shot.

"Hopefully this is the start of good things to come," he said.

Mordt also had birdies on his opening two holes, and then four more from Nos. 12-15 to join Maritz's late charge after Grace held the clubhouse lead for much of the day.

Also starting on the West Course, which was more than 300 yards shorter than the East, Grace did not drop a shot and capped his round with a 15-foot putt for eagle three on the par-5 ninth. He did miss a two-footer for birdie on 17, however, that would have given him a share of the early lead.

"It was just one of those things," Grace said. "I didn't really hit any bad shots today. I kept it in play from the tees and I kept hitting the greens which gave me the chances out there. I managed to roll a couple in so it was a good start."

Aiken threatened to set the pace on the East Course as he raced to 8 under before a par-bogey finish dropped him to a share of fourth with Kaleka.

Dutchman Floris de Vries, Welshman Stuart Manley, and English pair Jamie Elson and Robert Dinwiddie are part of an eight-way tie for sixth at 6-under 65.

Defending champion Charl Schwartzel of South Africa — the highest ranked player in the field at 32nd — began with a 3-under 68 on the East Course.

Only five of the leading 26 scores on Thursday were on the challenging 7,590-yard East Course.