Golf-Lingmerth's happy memories help him to Quicken Loans lead

June 29 (Reuters) - Sweden's David Lingmerth, buoyed by happy memories of the TPC Potomac, fired a five-under 65 to claim a one-stroke lead over a packed leaderboard after Thursday's opening round of the Quicken Loans National. Lingmerth won a Tour event in 2012 on the tight Maryland layout near Washington D.C. and once again relied on his accuracy off the tee. The Swede, without a top 10 finish on tour this season in 17 events, missed just two fairways as he carded seven birdies and two bogeys, including one at his closing hole, the par-three ninth. "That's one of the main keys out here," said Lingmerth. "It's a course where the rough is very penalising, very gnarly. You really got to stay in the fairway to have a chance to make birdies." Lingmerth said it was a happy homecoming. "Obviously, coming here is going to give me great feelings knowing I have won here on the Web," he said. "It seems to suit my eye really well." Six players were bunched one shot back, including Australian Marc Leishman, Canadian Nick Taylor, South Korean Sung Kang and Americans Troy Merritt, Johnson Wagner and Daniel Summerhays, who holed out from 105 yards at the par-four 13th. Another seven players were tied at three-under 67. Lingmerth, showing signs of a return to form with four top-20 finishes since late April, started at the 10th and ran off three birdies in a row from 13, capping the string with an 18-foot birdie putt at the 15th. The Swede knocked his approach inside four feet at 18 for another birdie and made the turn at four-under 31. He added birdies at the first and fourth, where he rolled in a 20-footer from the fringe, before making bogey at the last after an errant tee shot at the par-three ninth. Thirty-one players broke par but two of the top names in the field were not among them. Rickie Fowler posted an even-par 70, while this season's three-time winner Justin Thomas suffered a nightmare round. Thomas made five birdies but signed for a four-over-par 74, fueled by a quadruple bogey nine at the par-five 10th. Thomas pulled his tee shot left into heavy native scrub land beyond the thick rough. He failed twice to advance the ball and finally took a penalty stroke and dropped a ball, which he sent across the fairway into more trouble. He was tied for 93rd, nine strokes off the pace. (Reporting by Larry Fine in New York; Editing by Ian Ransom)