FIRST ROUND LEADERBOARD US unless stated -8 Hunter Mahan -7 JL Lewis -6 Craig Bowden, Robert Damron, Glen Hnatiuk (Can), Richard S. Johnson (Swe), Kirk Triplett

And the 15-year-old is well placed to become the first female for 60 years to make the cut at a men's PGA Tour event.

Wie lies seven shots behind leader Hunter Mahan - and a trip to St Andrews awaits the top finisher who has not already had an invitation to The Open.

"The back nine was awesome, I hit almost every green. I can improve a lot on the front nine," Wie said.

"Hopefully I can do that tomorrow. I feel a lot more comfortable. I'll go out and shoot a lower score tomorrow."

Wie, who is playing on a sponsor's exemption, is aiming to be the first female to qualify for the last rounds of a PGA Tour event since Babe Didrikson Zaharias in 1945 at the Tuscon Open.

If she can finish the weekend as the highest non-exempt player she will become the first woman ever to play at The Open Championship, after the Royal and Ancient relaxed their rules earlier this year.

But Mahan is at the top of the leaderboard after shooting a bogey-free eight-under-par 63 at the event in Illinois.

"It was a pretty easy round. I hit a lot of fairways and a lot of greens," Mahan said.

"I just had the green speed on the greens so I just had to worry about the lines and be aggressive. I didn't have to worry about too much out there."

Mahan is one shot ahead of fellow American JL Lewis, who is alone in second after a 64, with a group of five players a further shot back.