Pan holed a 100-foot chip for eagle on the reachable par-4 14th and also kept bogeys off his card for a 63 as he and Rai finished the second round at 14-under 128 at TPC Deere Run in Illinois on Friday.
They were one shot ahead of Englishman Harry Hall, who posted a 66.
Jason Day shot a 67 to be eight shots from the lead and tied for 47th. Harrison Endycott, the only other Australian in the field, missed the cut by two shots as he fired a 71 and finished at three under.
Jason Day has work to do to contend from tied 47th midway through the tournament. (AP PHOTO)
Rai shared the 54-hole lead in the Rocket Mortgage Classic in Detroit last week and wound up one shot behind Australian winner Cam Davis.
"I have been playing well tee-to-green for large parts of this season. That's kind of continued over the last few weeks," Rai said.
"And then a couple of weeks ago I spent quite a while on the green. My dad gave me a couple tips. Started working with John Graham last week, as well, a putting coach who is based out here.
"Putting all that together has definitely translated to on the course."
Still in the mix is Hayden Springer, who began the tournament with a 59.
Springer had 12 birdies and two eagles in his first 29 holes before he began to sputter, missing a 3-foot par putt and taking a double bogey late in his round as light rain fell
He had to settle for a 71 and and was among six players two shots off the lead, joining amateur Luke Clanton (67) ,Denny McCarthy (66), Eric Cole (68) Davis Thompson (67) and South Korea's Sungjae Im (64) .
"It wasn't too bad," Springer said. "It was a little windier today, probably played a little tougher. I kind of hit some bumps on the back nine, but more just mental errors and not making those short putts than anything else."
Florida State sophomore Luke Clanton extended his amazing summer run.
He drove the green on the 348-yard 14th hole to 15 feet for eagle. Perhaps more impressive was the way he rebounded from a double bogey on the par-4 sixth toward the end of his round with two straight birdies.
