Rory McIlroy shot a six-under-par 66 at the WGC-HSBC Champions in Shanghai but is six behind leader Hideki Matsuyama.
The four-time major winner carded seven birdies in round two on Friday at Sheshan International.
But that was only good enough to reduce his deficit by a single shot thanks to a brilliant 65 from Japan’s Matsuyama.
Scotland’s Russell Knox is three behind the leader after a second round 68 with English trio Richard Bland, Ross Fisher and Paul Casey also in contention.
Matsuyama, who is a career-high 10th in the world after finishing second and first in his last two events, had 10 birdies and four bogeys in an opening 66 and went one better here today.
Bland shot 68 on Friday – the same score as Fisher – to trail by five, one ahead of Casey after his two-under-par 70.
McIlroy took three shots from both the front and back nine, as he chases the victory he feels is necessary to have a chance of winning the Race to Dubai for the third year running.
The Northern Irishman is more than a million points behind Masters champion Danny Willett, who has a lead of more than 400,000 points over Open champion Henrik Stenson.
“I’ve been able to come back from six behind with 18 to play, so over 36 holes a lot of things can happen,” he said.
“Hideki’s playing very well and will be tough to catch, but from what I saw out there today, if I can keep that sort of golf going over the next two days I should have a chance.”
Knox, who made five birdies in his four-under round, said he was “thrilled” with his score, especially after the weather took a turn for the worse late in the round.
“I had a couple of chances there at the end, which I would have loved to have made,” the Florida-based Scot said. “Every shot was very difficult towards the end when it started raining, so I’m thrilled with four under.
“It was a little cold, but I’m built for this. As much as I would say I don’t enjoy playing in this weather, I’m good at it. I hope it’s like this at the weekend.”