Teenage amateur Su Dong shot a second successive two-under-par 70 to stretch his lead to seven strokes at the halfway stage of the 800,000-yuan Tianjin Championship, the Omega China Tour's penultimate event of the season.
Experienced Chinese Taipei invitees Tsai Chi-huang and Hsu Mong-nan, Hao Chunxi, Kong Weihai and amateur David Wei Wei all share second place on three-over at the Yangliuqing Golf Club.
Li Chao, the two-time Omega Order of Merit champion, and Xiao Zhijin are joint seventh on four-over.
The Canadian-educated Su, who only arrived in Tianjin on Wednesday after confirming his entry that day, started on the back nine and recorded 10 straight pars before bogeying hole two. He then bagged two successive birdies and another on his last hole.
"People say this course is long, but I love long courses. After my tee-shots, I'm only using a gap or sand wedge," said the big-hitting amateur, whose solitary bogey followed a stray tee-shot into the woods.
"Today, I had nine birdie chances in my first nine holes but couldn't convert because my putting was awful. I changed my posture and it started to feel better."
Su has twice finished third on this year's Tour, including memorably at the Sofitel Golf Championship in Nanjing, when he missed a four-foot putt to join playing partners Liao Guiming and Zhang Lianwei in a play-off.
On Saturday, the bulky big-hitter will play with Tsai, the former Asian Tour regular who won this month's Luxehills Golf Championship in Chengdu, and Hao, who will be playing in the finalflight for the first time.
"I'm really looking forward to playing with Tsai, because I like to make new friends on the golf course. I won't be distracted by his experience because he's not Phil Mickelson or Tiger," said Su, who splits his time between Beijing and Vancouver. "I'm playing to win, but so's everyone in the tournament."
Tsai, who shot 74 like Hsu, believes he can make up ground on the third day as he seeks his second successive victory on the Tour.
"I didn't score too well mainly because of my putting, but I'm getting there. I definitely want to shoot under-par on Saturday because I'd love to win again," said the Shanghai-based 39-year-old.
"I know Su Dong's a great player and finished third in Nanjing where I finished ninth. It's great to be playing with another one of China's top young stars, having played four rounds with Zhang Xinjun in Chengdu."
However, Tsai admitted the 7,345-yard, tree-lined championship layout was proving a tough test for the field.
"This is the longest tournament course I've played in my 20-year career. It's such a tricky layout because you can't even go for most of the par-fives in two shots. You can see by the scores how tough this course is. I think an even-par total or evenhigher could win the trophy."
Yuan Hao, joint second after an even-par first round, shot a 78to drop back to six-over. Liao Guiming, the current Omega Order of Merit leader, recovered his game to post a second-round 74 but is still off the pace at 10-over.
This week's event marks the Omega China Tour's first stop in Tianjin and the city's first major professional golf event since the 2004 Tianjin TEDA Open on the Asian Tour.
Leading second-round scores:
140 James Su Dong 70-70
147 Hao Chunxi 73-74, Tsai Chi-huang 73-74, Hsu Mong-nan 73-74, David Wei Wei 72-75, Kong Weihai 74-73
148 Li Chao 73-75, Xiao Zhijin 73-75
150 Zhang Xinjun 75-75, Wu Xujun 74-76, Wu Weihuang 78-72, YuanHao 72-78
151 Fu Tai 78-73, Jim Johnson 77-74.