Sergio Garcia claimed the first-round lead at the BMW Masters as Danny Willett got off to a slow start in his bid to overtake Rory McIlroy in the Race to Dubai.
With reigning European number one McIlroy not competing at Lake Malaren Golf Club this week, Willett can move to the top of the Race to Dubai standings by finishing 28th or better - ahead of next week's season-ending DP World Tour Championship.
However, the Englishman could only muster a level-par 72 on Thursday, leaving him eight behind Garcia, who equalled his lowest round on the European Tour this season.
After starting at the 10th, Garcia picked up shots on four of his first five holes and then responded to a bogey on 17 with another streak of birdies - registering five in seven holes from the first.
An Byeong-hun and Victor Dubuisson each carded bogey-free rounds of 65 to trail the leader by one, with Ross Fisher and Lucas Bjerregaard a shot further back.
Garcia said: "It's the kind of round that you are looking for.
"I drove the ball very well and that gave me a lot of opportunities to hit some good iron shots. It was a nice round."
Dubuisson was delighted with his efforts and said: "It's been a long time [since I have shot] a low score to start a tournament. To start with a seven-under feels great.
"I feel so good on the greens. When I read the line good, I feel like the putt can only go in the hole and you don't have this feeling much time during the year."
Like Willett, Justin Rose could move to the top of the Race to Dubai standings this week and the 2013 US Open champion birdied four of his last seven holes to reach five under.
Paul Casey also shot 67 with the aid of an eagle at the 14th, where he holed his approach shot, while Ian Poulter, Henrik Stenson and in-form rookie Matt Fitzpatrick are among those at four under.