McDowell, who won all three of his matches in Europe’s victory over the United States in September, carded a second successive 67 to lie 10 under par, three shots ahead of Gleneagles team-mate Ian Poulter.
The 35-year-old Northern Irishman fired five birdies and no bogeys and has now played his last 11 rounds at the venue in 49 under par after finishing third in 2011 and again 12 months ago.
Poulter, who was runner-up to Dustin Johnson last year and won the title when it was staged at Mission Hills in 2012, birdied four of his last five holes to match McDowell’s 67.
Double Masters champion Bubba Watson went one better with birdies at all five of the closing stretch in his 67 to finish six under alongside Japan’s Hiroshi Iwata, whose 65 was the best score of the week so far.
McDowell won the US Open in 2010 but has yet to win one of the WGC events and said: “It would be very special. The WGC’s are a special tier of events, there’s no doubt about that and this has always been one I had my eye on. This one and Doral (venue for the WGC-Cadillac Championship) are the two golf courses I feel I perform well on.
“But this is a world-class field. They are bunching up behind me and I have to get out there (today) and keep the pedal down and position myself for Sunday and give myself a sniff on the back nine.”
Asked to explain his remarkable scoring at Sheshan, McDowell added: “I think it’s the fact you don’t have to hit it a long way, you have to be accurate and I like these greens. I read them well here, this course is always so well presented and I just enjoy playing it. It wasn’t my best ball-striking round but I hung in there and I’m right where I want to be going into the weekend.”
In contrast, Poulter was delighted with his performance in his second tournament with new clubs as he looked to put an injury-plagued campaign behind him. “It was great. I played very, very solid,” said Poulter, who has slipped to 44th in the world rankings. “Probably the best I’ve played all year, which is very exciting.”