The FedEx Cup champion carded just one bogey during an excellent second round which saw him move up 17 places to T7
Rory McIlroy muscled back into contention at the WGC-HSBC Champions event in Shanghai with a stunning second round 66.
McIlroy shot level par during his opening round yesterday, carding no bogeys or birdies during a steady opening round.
However, today's performance saw him storm up the leaderboard with seven birdies and just one bogey to blemish an otherwise flawless second round.
The 27-year-old picked up three shots on the front nine, with birdies on two, five and seven sending him on his way to an assault on the top of the leaderboard.
A birdie on 11 was followed by back-to-back birdies on 13 and 14 to see him climb up the leaderboard and cut the gap on leader, Hideki Matsuyama.
A bogey on 16 was recovered with a birdie on the last and saw him close out the second round six shots off the pace and within touching distance of a top five finish.
"I feel like I actually hit the ball pretty similarly the first two days, I just holed a few more putts today," he told Nick Dye.
"I was able to take advantage of some of the good drives I was hitting. 66 in these conditions is pretty good and from the look of the leaderboard it's going to take a few more scores like that to have any chance."
Paul Casey, a former winner in China and who sits alongside McIlroy on the leaderboard, said: "There's a passion for golf here in China. I've loved coming here and their knowledge of the sport has grown through the years.
"We've seen that in their performances on the golf course in just the Pro-Ams, we're playing with better players. There's an easy barometer right there."