Defending champion Russell Knox and Swede Rikard Karlberg were just a shot off the lead midway through the opening round of the WGC-HSBC Champions at Sheshan International Golf Club.
Knox won on his World Golf Championships debut here 12 months ago and Karlberg was looking to repeat that feat as both men got to five under thanks to impressive birdie runs in Shanghai.
The course was holding up brilliantly after being battered by rain in recent weeks but the soft conditions led to some low scoring, with Americans Daniel Berger and Rickie Fowler leading the way at six under.
Scot Knox and Karlberg were then in the group a shot back alongside Englishman Paul Casey and American Bill Haas.
Berger had set the early pace with three birdies from the tenth and when he added further gains on the 14th and second he was in a share of top spot.
Fowler was going along beautifully, however, and after birdies on the 11th, 13th, 14th and 17th, he put his approach to the 18th inside six feet for another birdie. He then got on the green at the par five second in two for another birdie but Berger joined him at the top with a gain from ten feet on the seventh.
Berger had just two holes of his round left to play while Fowler had completed 13 holes.
Knox also started on the back nine with four pars but came to life with four birdies in a row from the 14th before adding another on the third.
Karlberg got off to a blistering start, birdieing the first, second, third, fourth and seventh to turn in 31.
Haas had six birdies and a bogey in his first 16 holes, while Casey recorded four birdies and a bogey to go with an eagle on the 14th in his opening 13.
Open Championship winner Henrik Stenson started with a bogey on the tenth but then found his touch, with gains on the 15th, 16th, 18th, second and third moving him to four under alongside England's Chris Wood and South African Dean Burmester.
Wood was blemish-free with three holes to play, making birdies on the 14th, 15th, 18th and fourth.
Burmester had a rollercoaster first 15 holes with eight birdies, two bogeys and an opening double on the first.
Richard Bland, Sergio Garcia and Francesco Molinari were then among the group at three under.
