Golf: Zach Johnson shot a 60 on a weather-delayed day at La Cantera and gave himself an excellent chance to defend his Valero Texas Open title.

Threats of lightning in San Antonio brought play to a halt for almost five hours, leaving the top 24 players on the halfway leaderboard to wait until late afternoon to start their rounds.

The long wait did little to upset former Master champion Johnson, though, as he moved from five under par for the week at the par-70, 6,896-yard Resort Course to take the overnight lead at 15 under after equalling the course record with an eight-birdie, one eagle round.

After a front nine of 30, the highlight of which was the two he scored at the par-four seventh, holing out from 84 yards, the American shot five birdies after the turn and as darkness descended Johnson gave himself an shot at a round of 59 with a 20-foot birdie putt at the 18th.

The putt came up short and the second 60 of his career went into the books instead.

Not only that, but by finishing before play was suspended due to the fading light, the 2007 Masters champion also gave himself a lie-in on Sunday while his rivals will be returning to the course to complete their third rounds.

Johnson has a three-shot lead over halfway leader Paul Goydos and first-round co-leader Justin Leonard, who were called in having played 12 holes.

Australian Marc Leishman was at 11 under, four under for the round, after 17 alongside American Scott Sterling, two under after 14.

Californian Goydos, seeking the third victory of his PGA Tour career, was a three-stroke leader at 12 under after 36 holes.

When he got his round under way after the delay, Goydos went backwards with bogeys at the third and sixth holes before getting the shots back with birdies at seven and 12 while Leonard was three under for his round.

Sweden’s Fredrik Jacobson and American Kent Jones were in a tie for sixth place on 10 under, both two under for the day having reached the 14th.

Brian Davis and fellow Englishman Greg Owen as well as Stephen Ames of Canada were at nine under with holes to play in the morning while Dustin Johnson went low with a 62 to get to the same mark.

Another Swede, Mathias Gronberg, did not take kindly to the delay, however, having slipped from a tie for second at nine under after 36 holes to six under after 48.

For those who did finish before the delay, 2003 US PGA Champion Shaun Micheel shot a seven-under 63 to get to eight under, as did Jonathan Kaye.

Further down the leaderboard, Sweden’s Richard S Johnson shot a two-under 68 to get to three under for the week.