Second-round leaderboard (Gbr & Irl unless stated, par 71): -6 M Siem (Ger), A Dodt (Aus) -5 T Bjorn (Den) -4 R McEvoy, S Hansen (Den), MA Jimenez (Spa), M Lafeber (Ned), E Molinari (Ita) -3 B Dredge, G Fdez-Castano (Spa), JM Lara (Spa), P Lawrie, R Rock -2 D Clarke, R Davies, L Donald, R Jacquelin (Fra), C Montgomerie, R Ramsay, J Sandelin (Swe)
By Peter Shuttleworth
BBC Sport at the Celtic Manor
Siem's only previous win was the 2004 Dunhill Championship
Marcel Siem is bidding for just his second European Tour win as his second round four-under-par 67 fired him joint top of the Wales Open leaderboard.
The German, who won the Dunhill Championship in 2004, enjoyed a steady round at the Celtic Manor to be halfway leader with Australian Andrew Dodt.
Dodt, the 2010 Avantha Masters champion, and Siem are one stroke ahead of Denmark's Thomas Bjorn.
Five players are in a group one shot further back.
They are England's Richard McEvoy, Dane Soren Hansen, Spaniard Miguel Angel Jiminez, Dutchman Maarten Lafeber and Edoardo Molinari of Italy.
Englishman Luke Donald recovered from joint 111th to tied 13th with a course-equalling record round of six-under par, 65.
The two-time Ryder Cup winner typified the rollercoaster scoring on day two in Newport as Donald's early round included a double bogey, a bogey and nine birdies.
Last week's Madrid Masters champion looked set for an early Wales Open finish after an opening round four-over par 75, but his superb round has put him in the chasing pack at two-under - four shots off leader Siem.
The German celebrated seven birdies - including one on the par-five second where 1999 Open champion Paul Lawrie needed 11, including eight putts - but dropped shots at two par threes and the par-five ninth.
The top of the Celtic Manor leaderboard had a local feel after the first round with Welsh pair Bradley Dredge and Rhys Davies chasing day one leader Chris Wood, but all three fell away as the front runners took on a continental flavour.
Paul Lawrie took a disastrous 11 shots at the second
Dodt was joint-second overnight after an opening-round 66, but, unlike his fellow day-one high-fliers, he improved his position with a steady one-under-par 70 on day two in Newport.
The 24-year-old Queenslander finished with two birdies in his last three holes to join Siem at the halfway summit at the Celtic Manor.
Experienced pair Bjorn and Jiminez, both Ryder Cup veterans, shot three-under rounds of 68.
It could have been better for the Spaniard but he dropped two shots at the dog-leg, 433-yard, par-four fifth.
Local boy Dredge, the 2007 Wales Open runner-up, and Welsh number one Davies both shot disappointing second rounds of 73.
The £1.8m Celtic Manor tournament is still waiting for its first home winner but Davies, who had gone 47 holes without dropping a shot, dropped three in his first two holes of the morning, while Dredge picked up just one birdie.
First-round leader Chris Wood, who boasted an unblemished card on Thursday, endured three double bogeys in his second round 76 as the Bristol golfer sank among the also-rans.
Colin Montgomerie, the Ryder Cup captain who will lead his European team against America here in October, shot his second successive one-under par round to move to two under.
The eight-time European number one, the subject of a tabloid story this morning about his private life, was steady and is in a chasing pack that includes fellow Ryder Cup heroes Donald and Darren Clarke.
Lawrie, meanwhile, had charged into contention from 63rd to joint fourth place, only two behind overnight leader Wood, in his opening eight holes before his round went dramatically downhill on the 610-yard second.
The 2002 Wales Open winner needed 11 shots, including an incredible eight putts, to hole.
He admitted it was "ridiculous" after signing for a 74 that sent him crashing out of the event at four-over par, just one above the three-over cut.
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