PITTSFORD, N.Y. — Morgan Pressel slogged through rain and muck to take the lead Saturday after two rounds in the LPGA Championship. Next up is a 36-hole marathon today.

“I run a lot,” Pressel said, laughing. “I’m in plenty good of enough shape to get through 36 holes tomorrow.”

She shot a 2-under 70 on Saturday at Locust Hill to reach 6-under 138 — two shots ahead of the top-ranked Park and Chella Choi in the second LPGA Tour major of the season.

Park had a 68 to give herself an opportunity to add to her three wins already this season, including the Kraft Nabisco Championship in April. Choi struggled with a 73 to relinquish her first-round lead.

Jiyai Shin, Amy Yang and Sarah Jane Smith were tied for fourth at 3 under. And there were seven more players at 1 under or better after two rounds, which should make for a long and topsy-turvy final day.

The change in schedule came after nearly five inches of rain fell Thursday, forcing officials to postpone the first round.

“It’s going to be very tough physically, I mean, especially walking on these wet fairways,” Park said. “There’s going to be many holes, but yeah, just try not to lose my focus.”

The forecast for today is promising, calling for sunny conditions and temperatures in the high 70s.

A light and intermittent drizzle fell through most of Saturday morning further drenching the 6,500-yard course. Then there were two brief but heavy downpours in the mid-afternoon before the rain finally relented after about 2:30 p.m.

That led to soppy fairways. It made the slick, overgrown rough even more difficult to hit out of. And even hitting the greens didn’t guarantee relief.

Pressel’s tee shot on the par-3 seventh plugged 20 feet below the hole, from where she two-putted. That was actually fine with her. With a laugh, she was thankful the ball stuck where it did because it was a better place than above the hole.

From Boca Raton, Fla., Pressel is attempting to end a string of eight straight majors won by Asian-born players.

Pressel also hasn’t won since claiming the Kapalua LPGA Classic in 2008. A year earlier, at the age of 18, she won the Kraft Nabisco to become the youngest LPGA player to win a major.

“It was a long time ago. I’ve been through a lot since then,” Pressel said. “A lot has happened in golf and life. But that being said, I’ve done it before. So I just need to go out there and remember that I can do it, and just get it done.”

Last year, Pressel struggled in dealing with injuries to her thumb and left wrist. This year, she has missed three of the past four cuts of tournaments entered. Her best finish of the season is a tie for 10th at Singapore in March.

Starting on No. 9 Saturday, Pressel birdied three of her first six holes to get to 7 under, before faltering. She bogeyed Nos. 16 and 18. Pressel nearly gave up another stroke on the short par-4 second, but saved par by sinking a 10-foot putt.

Pressel then padded her lead with a 4-foot birdie putt on the par-5 eighth.

“The tournament is only halfway finished, but I feel good about my approach to playing,” Pressel said. “It’ll be a long day, but I need to stay mentally focused.”

Park joined Michelle Wie in shooting the second-round’s lowest score in carding five birdies and a bogey-5 on No. 14.

With three wins already this season, including a major, the 25-year-old is carrying plenty of confidence into today.

“I would be less nervous than at the Kraft,” she said. “That kind of experience really helps going into major championships like this where you get the situation and you’ve experienced it before. You feel a lot more comfortable.”

In other events on Saturday:

Rookie takes lead at St. Jude: MEMPHIS, Tenn. — Rookie Shawn Stefani overcame a quadruple bogey and shot a 4-under 66 to take the third-round lead in the St. Jude Classic. The 31-year-old Texan blew a two-stroke lead with the quadruple bogey on No. 11, but rebounded with four birdies over his final five holes to move back atop the leaderboard. He had eight birdies to go with that quadruple bogey to reach 12-under 198 at TPC Southwind. Harris English was a stroke back after a 69, finishing out of the lead for the first time this week.

Frost up one stroke at Tradition: BIRMINGHAM, Ala. — David Frost birdied the 16th and 17th holes en route to a 6-under 66 and a one-stroke lead over Fred Couples after the third round of the Regions Tradition. Frost, the South African who won the Toshiba Classic in March for his fourth Champions Tour title, had four birdies on the final eight holes to move to 12-under 205 in the major championship. Couples, the Presidents Cup captain and World Golf Hall of Famer, shot a bogey-free 68.

Dutchman on top after shooting 67 in Austria: ATZENBRUGG, Austria — Dutchman Joost Luiten shot a 5-under 67 to extend his lead to three strokes after the third round of the Lyoness Open. Luiten had a 16-under 200 total. Spain’s Jorge Campillo and Eduardo de la Riva were tied for second. Campillo shot 66, and de la Riva had a 69.