Former Masters champion Zach Johnson shot a 10-under-par 62 to claim a share of the lead after the first round of the Justin Timberlake Shriners Hospitals for Children Open.

Fresh from winning last week's Valero Open Johnson, winner of the green jacket last year, continued his hot form with a brilliant bogey-free round.

He began on the back nine with birdies and picked up further shots at the 14th and 16th.

After the turn he carded five successive birdies from the first before completing his round with another at the ninth.

Fellow American Marc Turnesa also posted a 62, to lead by one from Michael Allen, Nick Watney, Matt Kuchar and Ken Duke.