James Morrison hit an eight-under 64 to storm to the top of the leaderboard at the BMW PGA Championship, while Rory McIlroy missed the cut.
The Englishman was in scintillating form during Friday's second round, notching six birdies and finishing with an eagle on the 18th to move into 12 under.
The 27-year-old, who is ranked 236 in the world, has a four-stroke lead at the Wentworth Club in Surrey, England.
Scotland's David Drysdale and English world No.2 Luke Donald are tied for second at eight under, while Ireland's Peter Lawrie and Alvaro Quiros of Spain are tied for third a further shot back.
Andrew Dodt is the best-placed Australian, tied for 30th at two under after a one-over 73.
Apart from posting his second consecutive round of four under, there was more good news for Donald as world No.1 McIlroy missed the cut.
The Northern Irishman started Friday at two over and hit six bogeys and two double bogeys to end his tournament at nine over.
McIlroy was just two over through nine but four straight bogeys around the turn ended his chances of remaining in the tournament.
Donald will now overtake McIlroy as world No.1 if he can finish in the top eight.
McIlroy was joined by his compatriot Graeme McDowell in missing the cut.
McDowell, who is ranked 18th in the world, shot a one-over 73 to finish at three over, missing the cut by two shots.
There is a group of eight players at six under, sitting behind the top five ahead of Saturday's third round.
That group includes England's Justin Rose, Italian Francesco Molinari, South African Branden Grace and Spaniard Rafael Cabrera-Bello.
World No.3 Lee Westwood (one over) just made the cut despite dropping 24 places on Friday.
Apart from Dodt, Brett Rumford (even par) and Richard Green (one over) are the other Australians to make the cut, while Marcus Fraser (two over) and Matthew Zions (three over) failed to make the weekend.