Scott Jamieson produced a remarkable recovery to hold a three-way share of the lead with Francesco Molinari and Thomas Pieters at the halfway point of the BMW PGA Championship as Johan Carlsson surrendered his advantage.
Carlsson had led the way after the opening 18 holes at Wentworth with a six-under 66, but could only card a 73 to drop back to four under, three shots adrift of the leading trio.
Pieters, having bogeyed the third, immediately recovered that dropped shot a hole later and went on to make gains at the ninth and 12th before holing out from the fringe of the green at 17 to take the outright lead at that point.
But the Belgian has to be content with a tie at the top after Jamieson and Molinari's respective efforts.
Jamieson bogeyed the first and then carded a double at the third to fall five shots off the lead, and the signs did not look promising after he went birdie-bogey on the fourth and fifth.
However, a stunning surge that featured six birdies in seven holes vaulted him into contention. The Scot went close to carding an ace at the 10th and would have held the outright lead if not for his inability to get up and down from the bunker at 15.
Molinari, having posted a five-under 67 on day one, went bogey-birdie-bogey on three, four and five, before a gain at 13 put him level par for the round. The Italian finished strongly, with back-to-back birdies at 17 and 18 moving him level at the summit.
Germany's Maximilian Kiefer is a shot off the pace despite carding five birdies and an eagle - which came at the 12th - a bogey at the 15th putting him fourth with a 68.
Carlsson's one-over effort dropped him two strokes adrift, level with Henrik Stenson, Lee Westwood, Branden Grance and An Byeong-hun.
A stunning approach shot helped Westwood birdie the seventh, his other gains at four, nine and 12 helping him move into a share of the lead, but he was another to fall victim to the 15th.
His compatriot Justin Rose eagled the last to make the cut at two over through 36 holes, though world number 28 Tommy Fleetwood did not enjoy similar fortune, his tournament ending after he went five over for the first two rounds, joining Martin Kaymer in having his tournament ended early.