Henrik Stenson was taking the media through his round when a cell phone blurted out "GPS signal lost". "It's OK mate. Just turn left," replied Stenson. The Swede had no such directional issues in the second round of the South African Open as he went straight to the top of the leaderboard.

Stenson took another big step in his bid to climb from 113 in the world to his once career high of fourth as he followed up his opening 66 with a 65 to lead on 13 under par going into the weekend at the Serengeti Golf and Wildlife Estate.

The round was suspended because of lightning, and will resume on Saturday morning at 7:30am. The third round is scheduled to start no earlier than 10:30am and off two tees.

All of which makes Stenson a very happy man at four strokes clear of another Swede in Magnus Carlsson, and with first round leader Merrick Bremner also at nine under with four holes to play.

"There's still a lot of golf to be played. I've put myself in a nice position going into the weekend, and I'm looking forward to it. I'm eager to win," said the Swede, who is looking to become only the eighth foreigner to win the South African Open, and the second Swede to do so since Mathias Grönberg in 2000.

And the way Stenson is driving the ball at the moment he will be hard to stop on the weekend.

"I've hit a lot of good drives. I counted eight good drives in the first round, and that's probably as many as I hit the entire 2011 season. It's nice to get the feel back with the driver."

After what he described as a "trembling start", Stenson made his first decent putt and his first birdie of the round on the 15th. He went on to make a further four birdies in six holes over the turn.

"Then I finished with a bit of fireworks on the eighth. Great drive – nailed it down the middle into the wind and then a super six iron to eight feet and made the putt for eagle," he said.

Charl Schwartzel is at six under with four holes to play, and Martin Kaymer is at four under also with four to play.