Jordan Spieth posts round-of-the-day 63 at the WGC-HSBC Champions

World No 2 Jordan Spieth feels he's now capable of adding a sixth title to a remarkable 2015 after surging back in to contention at the WGC-HSBC Champions.

The 22-year-old, who can replace the absent Jason Day at the top of the world rankings with a top-13 finish this week, produced a round-of-the-day 63 to move within three strokes of the lead at Sheshan International.

Spieth had expected to be rusty after his longest lay-off for 10 years, going two weeks without touching a club after helping the United States retain the Presidents Cup in Korea last month.

That showed with 10 birdies and six bogeys in opening rounds of 68 and 72, but the FedEx Cup winner was close to his best on Saturday, even though he felt a number of good opportunities went begging.

"You almost feel that (ten shots back) you're out of the tournament and almost feel like you're playing the golf course for yourself," Spieth said.

"I want my attitude to stay the same as today, so even though I feel now involved I need to almost approach the round like I'm just playing the golf course.

"I can build on this year with a swing that was certainly capable today, and if those putts go this could be mine tomorrow."

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Having reached the turn in 32 and picked up another gain at the 10th, Spieth surprising left a 12-foot putt at the 11th inches short before sinking a birdie putt from twice the distance on the next.

The American picked up another shot on the par-five 14th before a superb iron shot left him a tap-in on the 15th, while his short game helped him save par on the 17th after a wayward tee shot.

Spieth found the green at the par-five last in two, with a two-putt birdie from 15th feet taking the Masters and US Open champion to 13 under for the tournament.

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"I'm still working pretty hard on a couple of moves on my swings and my putting stroke, but that work I've put in over the past week all came together today," Spieth said.

"I've struggled to shoot lower than two or three under on this golf course in the past couple years, but today was the day to do it. Ball in hand, very little wind and some gettable pins.

"It was extremely stress-free, so all-in-all it was the type of day that you really want to have every time you tee it off and it doesn't come out very often."

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