Rory McIlroy led the WGC-HSBC Champions by two shots after an opening-round 65, an advantage he increased to three shots through nine holes in Friday's second round.
Things changed quickly at Sheshan International Golf Club, though, as McIlroy's poor finish combined with Dustin Johnson's record-tying round suddenly left the Ulsterman five shots off the pace at the halfway mark.
The former world No. 1 started slowly Friday but appeared to jump-start his round with three consecutive birdies from Nos. 6-8, making the turn at 10 under. Those would prove to be his final birdies of the day, however, as bogeys at the 11th and 15th holes were followed by another on the par-5 18th. With an even-par 72 Friday, McIlroy was the only player among the top 22 names on the leaderboard who failed to break par during the second round.
'Obviously played nicely the front nine and then started to hit a lot of sloppy shots on the back,' McIlroy told reporters following a round in which he failed to reach any of the final six greens in regulation. 'I just hit a couple of bad shots and then I guess I let it affect me a little bit and then I started to doubt myself sometimes. I didn't hit a lot of quality shots on the back nine.'
Still in search of his first win of 2013, McIlroy now shifts from tournament leader to a member of the chase pack. At 7-under 137, the 24-year-old is tied for second alongside Americans Boo Weekley and Bubba Wason, with a six-player group just one shot further back, headlined by Sergio Garcia, Graeme McDowell and defending champion Ian Poulter. All of them are trailing Johnson, who tied the course record with an 9-under 63 Friday and at 12 under holds a five-shot lead through two rounds.
Despite his late-round struggles, McIlroy remains optimistic about his chances heading into the weekend.
'It would have been nice to play a bit better and start tomorrow with a few more shots in hand,' he added. 'But I guess I'm in decent position ... and still have a great chance at winning this tournament.'