Swede Hedblom halfway leader at Perth International golf
File picture shows Swedish golfer Peter Hedblom (R) with his caddie John Dempster during the first round of the 113th US Open at Merion Golf Club in Ardmore, Pennsylvania on June 13, 2013
Hedblom, who shared in a four-way lead after the opening 18 holes, fired three-under 69 to claim the outright lead at seven-under 137.
The Swede was two shots clear of Englishman Ross Fisher, who carded the lowest round of the day shooting five-under 67.
While England's Paul Casey missed the cut, Hedblom was dreaming of a fairytale win in the $2 million Perth tournament at Lake Karrinyup.
Casey, a 12-time winner on the European Tour, missed the cut by one stroke after finishing his second round at three-over.
The next two days will be make-or-break for Hedblom, who needs to win the tournament to retain his European Tour card for next year.
“I don't really have anything to lose. If I want to play another full year on Tour, I need to win," Hedblom said.
"So I just have to go for it and have fun. I think I'm better when I'm up in the lead rather than trying to shoot a low score to try to get into the lead.”
Denmark's Soren Hansen (71-69) was among five players at four-under 140, while world number 21 Dustin Johnson of the United States was six shots off the pace after a two-over 74.
American defending champion Bo van Pelt was at three-under for the tournament.
Fisher's highlight of the round was a 20-metre chip-in from the bunker on the par-3 eighth.
"It was a decent lie but it was coming down the green and downhill, so I knew it was going to be pretty quick," Fisher said.
"I'm still getting used to the greens. Obviously, they are a lot quicker than what myself and all the Europeans are used to."
A member of the European Ryder Cup team in 2010, Fisher has had a top-10 finish on the PGA Tour and another four on the European Tour this year.