Karlberg had been one of three overnight leaders at five under par, along with Simon Dyson and Liang Wen-chong, and four birdies in his opening six holes yesterday saw him open up a gap over the rest of the field. His lead could have been greater had he not dropped shots at the 18th and fifth, having started his round at the 10th.
Karlberg heads a chasing group of four on seven under par. England’s Matthew Baldwin shot a 69 to be three under on the day, with China’s Liang Wen-chong carding a round of 70.
Ireland’s Michael Hoey and Frenchman Alexandre Kaleka were the day’s big movers as rounds of 67 moved them into contention.
But it was a difficult day for Simon Dyson. The Englishman, who has shown an upturn in form in recent weeks after a tough start to the year, had been level with Karlberg and Liang after the opening round.
But a double bogey on the 17th proved costly as he dropped back to three under for the tournament after his 74.
Karlberg, seeking his first in on the European Tour said: “I made a really good start to the round and then when the conditions got worse I managed to hang in there and then had a great finish with two birdies in my last few holes which is very satisfying obviously.”
* Meanwhile, Mark Wiebe carded a superb second-round 65 to earn a share of the halfway lead with Bernhard Langer in the Senior Open at Royal Birkdale.
The 55-year-old American started the day at level par but picked up six birdies in his round, including four on the back nine of the Southport course, to leap to the top of the leaderboard at five under alongside Langer.
The German posted a score of 67 on the day to move to five under par, and would have held the outright lead had it not been for a double bogey on the sixth.
He said; “I played like the weather today, pretty good. I just had one little blemish with a double bogey where I missed the green and double hit my chip shot. Otherwise it was a really good round. I hit a lot of good shots and putted much better today. So I’m very pleased with the position I’m in at the halfway point.”
Langer and Wiebe are one shot clear of South Africa’s David Frost while first-round leader Gene Sauers is among a group of three a shot further back on three under for the tournament.
The trio also includes Australia’s Peter Fowler and Ireland’s Mark McNulty.
Scotland’s Sandy Lyle is at two under while America’s Mark O’Meara, who won the 1998 Open Championship at Royal Birkdale, is two over.
Tournament debutant Colin Montgomerie is three over after a round of 71, which included a double-bogey six at the par-four third.
* Russell Knox shot an impressive round of 59 in the Web.com Tour’s Albertsons Boise Open in Idaho yesterday.
The 28-year-old Scot recorded eight birdies and two eagles to become only the fifth player to shoot 59 in the 24-year history of the tour – but the second to do so in the last three tournaments.