|WGC-HSBC Champions third-round leaderboard|
|-11 G McDowell (NI), -10 H Iwata (Jap), -9 M Kaymer (Ger) B Watson (US), -8 R Fowler (US), T Clark (SA), -7 I Poulter (Eng) T Olesen (Den); Selected others: -4 L Westwood (Eng), -1 P Reed (US), A Scott (Aus), S Gallacher (Sco) level J Donaldson (Wal) +2 T Fleetwood (Eng) E Els (SA)+3 J Rose (Eng)|
The Northern Irishman, 35, started off the day at Sheshan three shots clear of the field but could only manage a 71 for an 11-under total.
Japan's Hiroshi Iwata, in his first WGC event, finished with two birdies in his last three holes and is one back.
Masters winners Martin Kaymer and Bubba Watson are both on nine under.
"I hit a lot of good putts today that didn't go in and that's probably the main difference between shooting one under and three or four under," said McDowell.
"I was generally happy with the way I hit the golf ball. I didn't quite score as well as I did the last couple of days but I really gave myself some confidence that I can get the job done tomorrow."
McDowell started solidly with pars at his opening three holes and he followed up a birdie at the fourth with another at the seventh before dropping a shot at the eighth.
Germany's Kaymer shot a 66 thanks to birdies at 14, 16 and 18, although he dropped a shot at the 15th while Watson also finished strongly with four birdies in his last five holes.
But American Watson, who had been looking dangerous, had a double-bogey at the 10th and then dropped a further shot at the 12th. Although his late flourish left him in a good position, he was unable to overhaul McDowell.