Los Angeles: Zach Johnson, eager to focus on his game after the demands of Ryder Cup captaincy, fired a 10-under par 62 on Thursday to share the lead in the US PGA Tour American Express tournament with Sweden’s Alex Noren. Two-time major winner Johnson had 10 birdies on the La Quinta course, one of three in use over the first three days of the tournament in the California desert east of Los Angeles. After stringing together six straight birdies from the fourth through the ninth, Johnson rolled in an eight-foot putt for his final birdie of the day at the 17th to take the solo lead. Noren joined him after a more up-and-down day at La Quinta, where he was seven-under after his first seven holes thanks to five birdies and an eagle, then hit out of bounds to take a double bogey at his eighth hole, the par-four 17th. Five birdies coming in, including two to cap his round at the eighth and ninth, pushed him to a share of the lead in pursuit of a first US tour title to go with his 10 European Tour victories. Johnson, the 2007 Masters champion who claimed the last of his 12 tour titles at the 2015 British Open, missed the cut last week in Hawaii. But he said he was excited by the prospect of a season more focused on his game. “Put a lot of good work in as of late,” said Johnson, whose US team fell to Europe in Rome in last year’s Ryder Cup. “Actually been a lot of normal golf work, given what happened last year with what I was responsible for, which was awesome. Now it’s time to get back to work. I’ve enjoyed the work. I’ve enjoyed the sweat.”