Ernie Els will defend his Open title at Sandwich next week

Ernie Els increased his overnight lead to head the field by four strokes on 11 under par after the second round of the Scottish Open.

The South African maintained his impressive form on the eve of defending his Open title, making just one bogey as he carded a 67.

"It's a pretty nice position at the moment," said Els.

"I've been in it quite a few times and know what I have to do. I have to play my game and try and build on my lead if I can."

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Phillip Price of Wales moved into second place on seven under with a 68, one stroke ahead of Terry Price of Australia and South African Tim Clark.

"I struggled on the front nine and made quite a few mistakes, but it was a nice finish," said Price.

"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."

Is it going to take something out of me? I don't particularly care right now Ernie Els

Els was among the late starters but started strongly with three consecutive birdies from the par-three fifth.

He dropped his only shot of the day at the 12th, but further birdies on 13 and 14 took him to 11 under.

And Els insisted he was only concerned about his performance at Loch Lomond, and not the third major of the year at Royal St George's next week.

"Is it going to take something out of me? I don't particularly care right now," said Els. "I want to play as well as I can.

"The start of the year and all the miles I did, if that did not take it out of me then I don't think this will."

2nd Rd Leaderboard -11 Ernie Els -7 Phillip Price -6 Terry Price -6 Tim Clark

American Phil Mickelson made the halfway cut by a shot with five birdies and an eagle in his round of 68.

"I certainly wanted to play another couple of competitive rounds heading into the Open," said Mickelson.

Colin Montgomerie was despondent after his second-round 70 and complained about the state of the greens for the second day running.

"They were not very good, not much better than yesterday," said Montgomerie.

"Only two birdies each day is not enough and proves I'm not putting well enough."

There were also a number of withdrawals and retirements, most notably Retief Goosen and Ian Woosnam, who both pulled out with back injuries.

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Jay Don Blake, seeking his first victory in 12 years, scored a two-under-par 68 in difficult conditions to hold on to his one-shot lead at eight-under after round two.

Blake's only previous win came at the Shearson Lehman Brothers Open in 1991.

Patrick Sheehan signed for a five-under 65 and is tied for second with Jerry Kelly and Brett Quigley, who both shot 67s.

Seven players are another two shots back, including Loren Roberts, a two-time winner of this event.

Blake - who lies 192nd on the money list - missed the cut in his last three events, while his best finish this season was a tie for 28th at the Capital Open.

"I played well today," said Blake. "It's very tough out there with the way the wind is blowing the way it is.

"The iron shots are severe. I was just trying not to do anything crazy."