Justin Rose posted a 6-under 66 on Friday and is alone in second place at 9-under-par 135. One shot behind Rose is Kurt Barnes, who also carded a second-round 66.
Steven Bowditch (69), Tony Carolan (69), Greg Chalmers (67), Simon Khan (66)) and John Senden (68) are knotted in fourth place at 7-under-par 137.
Pike, who matched the course record on Thursday with an 8-under-par 64, parred his first two holes Friday before breaking into red figures with a birdie at the par-3 third.
At the par-5 sixth, Pike knocked his third in a bunker and only blasted out to 25 feet. He sank that birdie putt, then made birdie at the seventh to reach 11 under par for the championship.
The 21-year-old Australian parred his final two holes on the front side, then returned to the 10th, his first hole during Thursday's first round. In round one, Pike eagled the hole to fly out of the gate, but on Friday, he only managed a birdie.
Pike padded his lead with his second birdie in as many rounds at the 606-yard, par-5 14th. He got to 13 under par and owned a four-shot lead over Rose, who finished in the morning.
Things fell apart quickly for Pike down the stretch. He bogeyed both the 17th and 18th holes to see his once-strong four-stroke cushion get cut in half with half the tournament to go.
The amateur does not even seemed to be greatly impacted by his position on the leaderboard.
'Just because I'm leading or just because there might be top-20 golfers breathing down my neck I'm not going to go out there and hit a thousand balls tomorrow morning to try to get better,' said Pike, who did not even take up golf seriously until last year. 'I've shown for the first two days that I can play and if I do it again, if I shoot 11 under again, which is doable, it's going to be hard for one of those guys to run over the top of me.'
Rose played the back nine first on Friday and tallied three birdies in his first six holes. He bogeyed the 18th for the second straight day, but made the turn at 2-under-par 34.
Rose started his second nine in a similar fashion to his first nine. He birdied one, three and four, then dropped a shot at the fifth. The Englishman birdied six and nine to move into second place.
'I played the par-threes really, really well today,' Rose said. 'I made three twos, and hit iron shots close on all of those birdies so anytime you make three twos it tidies up your score pretty quick.'
Frenchman Raphael Jacquelin only managed an even-par 72 on Friday, but is alone in ninth place at 6-under-par 138.
Aaron Baddeley (71), Peter Lonard (71), James Nitties (68), Carl Suneson (71) and Peter Wilson (74) are tied for 10th place at minus-7.
The 36-hole cut fell at 1-over-par 145 and 67 players made it to the weekend. The most notable golfer who failed to make the cut was former U.S. Open champion Michael Campbell. The 2005 U.S. Open winner struggled to a 1-over 73 on Friday and completed two rounds at 3-over-par 147.