Louis Oosthuizen and Brendon Todd share Byron Nelson lead

South African Louis Oosthuizen is joint leader with American Brendon Todd after the third round of the Byron Nelson Championship.

Oosthuizen, the 2010 Open champion, fired a six-under-par 64 at the TPC Four Season Resort on Saturday to share the top of the leaderboard on 10 under.

"I am playing really well this week and today was a good scoring day for me," the 31-year-old said.

"I am putting really well and I also hit the ball well with the irons."

Oosthuizen enjoyed a run of consecutive birdies on the 14th, 15th and 16th to cap a superb round which moved him 14 places up the leaderboard in the US PGA event.

Overnight leader Todd did enough to retain a share of top spot, but needed a birdie on the 18th to do so after a bogey on the fourth saw him fall behind. He signed for a two-under 68.

Oosthuizen carded the best round of the day, but James Hahn of the United States was one bogey on the 11th away from matching it.

A stunning run of birdies between the 12th and 16th catapulted him up to a share of third place alongside Gary Woodland and Mike Weir.

Britain's Paul Casey, who fired a nine under par 27 on the back nine on Friday to move into the joint lead, dropped down to 27th on three under after a three-over par round of 73.