Classy Kaymer six clear

The classy German led by just one stroke overnight, but he put daylight between himself and the star-studded field as he raced to the turn in 31 and picked up two more shots coming in to close on 20 under par.

Kaymer has not dropped a shot since the 12th hole in the opening round, although he was staring at a double-bogey after getting into trouble at the 10th until he holed a magnificent bunker escape to salvage his par.

Young Belgian Thomas Pieters remains his closest challenger despite passing up a series of makeable birdie chances in a two-under 70, but Rory McIlroy endured another frustrating day with the putter as he laboured to a 71 which left him eight shots off the pace.

After Ryder Cup stars Victor Dubuisson (64) and Jamies Donaldson (65) had given an indication of the scoring conditions to the later starters, Kaymer raced out of the blocks with two opening birdies before adding three in four holes from the fifth.

The US Open champion appeared likely to open the door for the field following a wayward approach to the long 10th, but his perfect 20-yard bunker escape kept him at 18 under par.

Kaymer immediately capitalised on his good fortune as he rolled in another birdie putt at the next, and a stunning approach to 18 inches at the 13th set up his seventh birdie of the round.

He was unable to add to his birdie tally over the final five holes, but the world No 12 had already done enough to put himself firmly on course for his fourth victory here in six starts.

Pieters did his best to keep pace with the leader early on, matching Kaymer???s birdie at the second and adding another at the third before he closed out a confident, outward 33 with a three at the ninth.

But the putts dried up for the 22-year-old after the turn as he could not better par over the next seven holes, and his frustration was evident when a poor tee shot at the 17th led to his lone bogey of the day.

Pieters saved par from 10 feet at the last to ensure his place in the final group alongside Kaymer on Sunday, while Bernd Wiesberger and Alexander Levy closed within one stroke of the Belgian.

Wiesberger handed in an entertaining seven-birdie 66 and Levy, twice a winner on the European Tour last season, finished birdie-eagle to return a 67 and join the Austrian on 13 under.

Former Masters champion Charl Schwartzel is a shot further adrift alongside Gary Stal after three birdies over the last four holes capped a faultless 65, but McIlroy???s challenge faded further with every putt that grazed the edge of the hole.

The world No 1 again looked in fine touch from tee to green, but he could only convert birdie chances at the sixth and 12th before giving one back at the 13th.

McIlroy missed only two fairways and one green in regulation, but he cast a disconsolate figure as he trudged off the 18th after tapping in his 34th putt of the day.