Ernie Els maintained his impressive British Open build-up with a four-under-par 67 in the Scottish Open second round on Friday, stretching his lead to four shots.

Two clear overnight after a blemish-free 64 in Thursday's rain-disrupted conditions, Els mixed five birdies with a bogey to end another damp day at Loch Lomond on 11-under 131.

The British Open champion, among the late starters, reeled off three consecutive birdies from the par-three fifth to reach the turn in three-under 33.

Although he dropped his only shot of the day at the 415-yard 12th to slip back to nine under, the South African strengthened his grip on the tournament with further birdies on 13 and 14.

"After two weeks' layoff, I'm playing pretty well and I'd like to keep it that way," said Els, whose last tournament was the Buick Classic in June when he tied for 11th place.

"I've been in this position quite a few times, so I know what I've got to do -- you've got to stay in the moment and not get too ahead of yourself.

"That's what I've been working on the past couple of months, especially with Jos (Vanstiphout, the Belgian sports psychologist).

GOOD SIGN

"So far, I've been playing close to my best and that's a good sign," added Els, who launches his British Open defence at Royal St George's next Thursday.

Britain's Phillip Price, winner of last week's European Open in Ireland, and Australia's Terry Price, who birdied the last, shot matching 68s to share second place at seven-under 135.

"I struggled on the front nine and made quite a few mistakes, but it was a nice finish," said Ryder Cup player Phillip Price, who birdied three of his last five holes.

"I've been playing well this season, and it's probably the putting which has made the difference, because I've been able to keep the momentum going," added the Welshman, who has produced five top-10 finishes in 11 European Tour starts this year.

The halfway cut was made at three-over 145, with 79 players advancing to the third round.

U.S. amateur champion Ricky Barnes and South African Trevor Immelman (both on 146), Britain's Justin Rose (149) and Australian Adam Scott (150) were among those to miss out.

World number eight Phil Mickelson, while not in contention for the Scottish Open, was delighted to make the cut after improving to a 68 on Friday.

SET SIGHTS

The left-handed American, who had struggled in an opening 76, finished at two-over 144 and set his sights on an even better performance over the weekend.

"I feel like I have two rounds to improve my position," said the former world number two. "I wanted to play a couple more competitive rounds going into next week's (British) Open championship.

"I'm not really in contention (at Loch Lomond) but I played really well today," added Mickelson, whose round included five birdies and an eagle three at the 510-yard third, where he struck a three-iron approach to 15 feet.

"I had a potential really low round out there, but I made a few too many (four) bogeys."

Earlier, former major winners Retief Goosen and Ian Woosnam withdrew from the second round, citing bad backs.

Goosen, the 2001 U.S. Open champion, pulled out after running up a bogey five and a triple-bogey seven in his first three holes.

Woosnam, winner of the 1991 U.S. Masters, also withdrew after three holes, having dropped three shots at the par-four 10th, his first hole of the day.