Hideki Matsuyama went on a birdie blitz to take the lead on day two of the WGC-HSBC Champions, but Russell Knox continued to mount a fine defence of his title at Sheshan International Golf Club.
The Japanese broke into the top ten on the Official World Golf Ranking this week and was showing that his game has a bit of everything over the first two days in Shanghai.
After an opening 66 that contained just four pars, he took his birdie count for the week to 18 in 32 holes to get to 12 under as round two moved towards its conclusion.
The 24 year old started with a bogey but then made birdies on the second, third, seventh and eighth before dropping another shot on the ninth. He was giving himself lots of chances with some fine iron play and made further gains on the tenth, 11th, 12th and 14th to open up a two-shot lead over American Bill Haas.
Knox was then a further shot back, one clear of England's Richard Bland and two ahead of overnight leader Rikard Karlberg, Dean Burmester and Daniel Berger.
Haas made a fast start with birdies on the second, third and fifth and back-to-back gains on the tenth and 11th moved him to ten under with seven to play.
Knox's 66 on Thursday was the best opening round from a defending champion at this event and he turned in 33 as he looked to follow it up.
The Scot birdied the second but gave the shot straight back before setting up a tap-in birdie with a stunning approach to the fifth. Another gain came on the seventh and he played the par five eighth beautifully, going short off the tee and laying up to allow himself to set up another short-range birdie.
Bland was making his World Golf Championships debut in his 396th European Tour event and made birdies on the 11th, 13th and 14th before holing a 15-footer on the 16th. An eight-footer on the 18th gave him a 12th birdie of the week but he bogeyed the first and had three holes left to play.
Karlberg turned in 34 to stay in a share of the lead but then made bogeys on the first, fourth and fifth.
Berger was the only player in the field still bogey-free for the week and made a single gain in his first ten holes while South African Burmester was three under for the day through 11 holes.
World Number Three Rory McIlroy had got the putter working and he made five birdies in 13 holes to join the group at six under along with Francesco Molinari, Paul Casey and Xinjun Zhang.
Open champion Henrik Stenson, Ross Fisher, Lee Westwood and Rickie Fowler were then all at five under.
