Scott Henry was sitting on the fringes of the leading 20 heading into the weekend's action at the Joburg Open at Royal Johannesburg & Kensington.

The former Scottish Strokeplay champion from Clydebank carded one birdie and 17 pars in a solid but uneventful one-under 71 over the East course for a seven-under aggregate of 136.

That left Henry, who is striving to regain his full European Tour playing rights, in a share of 21st, five shots behind host nation hopeful Wallie Coetsee.

Ranked a lowly 509th in the world, Coetsee, who ended a 17-year title drought on the Sunshine Tour with victory in Zambia last season, added a six-under 65 on the West course to his opening 66 and moved to the front with a 12-under tally of 131.

South African players have won the last five stagings of the Joburg Open, and six of the last eight, but 42-year-old Coetsee was probably not tipped by many to be the local frontrunner this week.

"There were no cameras on me the whole day, so it was quite easy out there," said Coetsee, who leads by a shot from his compatriots, Garth Mulroy and Tjaart Van der Walt, as well as Englishman Simon Dyson. "This is a marathon, not a race. You have to pull the horse back a bit, you can't run too fast. We'll let the horse loose on Sunday on the back nine. For now it's about making solid pars and keeping the battery at 100 per cent."

Sean Jacklin, the Scots-born son of the decorated English golfer Tony, posted a 69 for his 137 total while Andrew McArthur was the only other Scot to make the cut on 138. Craig Lee, Chris Doak, David Drysdale and Blairgowrie amateur Bradley Neil all made early exits.

On the LPGA Tour, North Berwick's Catriona Matthew hoisted herself into a share of seventh during the second round of the Honda LPGA Thailand Championship.

The former Women's British Open champion made a telling thrust on her inward half and picked up birdies at 11, 13, 14 and 15 in a purposeful six-under 66.

That moved the 45-year-old on to a seven-under aggregate of 137 but she was still lagging seven shots behind Stacy Lewis, who stamped her authority on the event with a 64 to open up a three stroke lead.

After a slow start to her round, Lewis, the world No 3 and the winner of the Women's British Open at St Andrews in 2013, upped the ante with four birdies in a row from the fourth.

"It got off to a bit of a slow start, but about midway through the front nine I kind of caught fire with the putter and started hitting some shots close," said Lewis.