The Woodlands, Texas ? Vijay Singh shot a 6-under-par 66 Saturday and extended his lead over Darren Clarke to three strokes after three rounds of the Shell Houston Open. Singh, seeking his first U.S. tour victory since the 2000 Masters, is 18 under for three rounds, tying a tournament record set in 1980 by Curtis Strange.

The overall tournament record, 18 under by Strange in 1988, also is within reach.

Singh was nearly flawless for a third straight day and had a 198 total entering today’s last round.

Clarke of Northern Ireland trailed the Singh by two shots going into Saturday but lost ground with his 67 and was at 201.

Jose Maria Olazabal of Spain was next at 203. He had nine birdies in his 64, his best round of the year and the lowest round of the tournament at the TPC at The Woodlands.

Other international players in contention included Japan’s Shigeki Maruyama at 11 under after a 66. That was one shot better than South Africa’s Rory Sabbatini, who also had a 66, and Australia’s Greg Norman, whose second consecutive 68 left him eight shots off the lead.

Brandt Jobe, who lives near Dallas, had a 69 and was tied with Maruyama. His 205 made him the lowest-scoring American-born player. He has never won on the PGA Tour since turning pro in 1988.