Tom Kim and Brian Campbell penalised for playing each other's ball in Mexico

Tom Kim and defending champion Brian Campbell were both penalised two shots at the PGA Tour's Mexico Open after an unusual mix-up left them playing each other's golf balls out of the same bunker.

The pair found the same greenside sand at the par-4 18th hole at Vidanta Vallarta and played their recovery shots before it emerged, according to Golf Monthly, that Kim had struck Campbell's ball and Campbell had struck Kim's.

Under Rule 6.3c(1), a stroke-play infringement of this kind brings the general penalty of two shots, with the player required to correct the mistake.

The error turned what would have been pars into double-bogey sixes for both players, denting rounds that had otherwise been heading in the right direction.

Golf Monthly reported that the penalty dropped each man's tournament total from nine under to seven under, leaving them tied for 26th and seven shots off the pace.

Both comfortably survived the cut regardless. Campbell, who won last year's title in a playoff, will have been frustrated to lose ground in defence of his crown, but the damage was not enough to end his week.

The reported clubhouse leader after that stage was Andrew Novak, sitting at 10 under for the tournament, though the picture out on the course was shifting fast as the second round progressed.

At the top of a congested leaderboard sat Kihei Akina, the 20-year-old Brigham Young sophomore, who chipped in for birdie on his closing hole to post a 7-under 64, according to Yahoo Sports.

That effort moved Akina to 11 under for the tournament, level with Matthieu Pavon and Adrien Dumont de Chassart, with a sizeable portion of the field still out on the course at that point.

It was Akina's ninth round in the 67-or-better range across his last four PGA Tour starts, a run stretching back to the sponsor exemption that first brought him into the Wyndham Championship field.

He has already banked one top-10 finish on tour, at the Bank of Utah Championship, and described his week in Mexico in simple terms.

"I'm feeling more comfortable with each round played," Akina said.

His round featured three birdies on the par fives and an eagle at the drivable par-4 13th, where he found the green from 296 yards out.

"We had about 287 to the front of the green and that's what I was trying to hit," Akina said. "So just a nice, roasted draw mini-driver for me, landed in a perfect spot and rolled down to tap-in. So that was a bonus for me."

The performance also keeps Akina's progress toward a PGA Tour card on track. He has picked up seven points in the PGA Tour University program for underclassmen since the Wyndham Championship in August, earning one point for every cut made and one for every top-10 finish, taking his tally to 12.

Attention at Vidanta Vallarta now turns to the weekend, with Kim and Campbell looking to climb back up the leaderboard and Akina aiming to turn his hot putter and ball-striking into a maiden PGA Tour title bid.