World number one Lorena Ochoa and 14-year-old US teen were among five co-leaders after Friday's second round of the 1.3 million-dollar LPGA Navistar Classic.

Mexico's Ochoa, the defending champion, fired a four-under par 68 and Thompson, a ninth-grade schoolgirl trying to become the youngest winner in LPGA history, fired a 69 to stand on 10-under 134 after 36 holes.

Joining them atop the leaderboard were Britain's Laura Davies, who fired a 65 Friday; Taiwan's Yani Tseng, who matched a tournament record by firing a 63 in the second round, and Italy's Giulia Sergas, who fired a 65 on Friday.

Thompson, whose brother Nicholas plays on the PGA Tour, would snap the youth age mark for a full tournament winner of 18 years and nine months set by fellow American Paula Creamer in winning the 2005 Sybase Classic.

Thompson was last year's US junior girls champion and shared 34th in July's US Women's Open.

Sweden's Sophie Gustafson, who won last week, fired a 65 to stand alone in second, one stroke back of the lead pack. Among those two off the pace are Britain's Janice Moodie and US prodigy Michelle Wie, still seeking her first major stroke-play title.

Ochoa, who began on the back nine, had five birdies and two bogeys, taking a bogey at the sixth but answered at the par-5 eighth with a seven-foot birdie putt to claim her share of the lead.

"I'm really happy with my round," Ochoa said. "It was a little bit of a roller coaster, but I think what's important at the end of the day is I'm in a good position for the weekend. I'm excited to be up there."

Thompson answered a bogey at the fourth with birdies on three of the next five holes and dropped a 20-foot birdie at the 17th to share the lead.

"That fourth hole, that was a pretty stupid mistake. But, I bounced back and I made birdie next hole. So that was good. That definitely turned it around," Thompson said.