King Abdullah Economic City - Victor Perez followed his opening-round 65 with another on Friday to take a one-shot lead over his university roommate Gavin Green in the Saudi International.
Frenchman Perez, who won the Alfred Dunhill Links Championship last year and came second in the Abu Dhabi HSBC Championship last month, moved to 10-under par at the halfway stage.
The 27-year-old's University of New Mexico teammate Green, playing in the tougher afternoon session, followed his opening round 64 with a three-under par 67.
Perez started on the 10th and made four birdies in his first nine holes. He then traded two birdies with bogeys before draining a 20-footer birdie putt on the difficult par-4 ninth.
"Very pleased with the second round," said Perez. "I think it was important to keep the hammer down after an unexpected 65 in the wind yesterday. I think those were definitely the tougher conditions.
"This is the round where you have to try to take as much advantage as you can and put some points on the board, and obviously in a very good position for tomorrow."
Malaysian Green found all 18 greens in regulation despite playing in the windy afternoon conditions. However, as in his opening round, he made two three-putts for bogeys.
"I'm pleased with it for sure. A bit like yesterday, I had two three-putts, and hit 18 greens," said the 2017 Asian Tour Order of Merit champion.
"The wind picked up and conditions were a lot harder. The last few holes were like, whoa, almost a three-club wind. But I just hung in there and kept hitting nice shots."
"Playing with Victor tomorrow, I think it will be fun. It's just like college days again."
Overnight co-leader Graeme McDowell could not take advantage of playing early in calm conditions, adding a 68 to his first round 64 to sit eight under, one ahead of Italian Renato Paratore who shot 65.
Northern Irishman McDowell said a slow-play warning after he gave an interview to one of the tournament broadcasters while walking down the fairway distracted him.
Defending champion Dustin Johnson was five back after shooting 68, while world number one Brooks Koepka sits back in 38th at one-under following his 69.
Among those who missed the cut in the $3.5 million event were world number 12 Patrick Reed and England's Lee Westwood, who recently won in Abu Dhabi.
Germany's Martin Kaymer, a former world number one, had the best card of the day, a six-under par 64 that helped him climb 76 places to tied 18th.
Select second-round scores Friday in the $3.5 million Saudi International at the par-70 Royal Greens Golf Club course:
130 - Victor Perez (FRA) 65-65,
131 - Gavin Green (MAL) 64-67
132 - Graeme McDowell (NIR) 64-68
133 - Renato Paratore (ITA) 68-65
134 - Jazz Janewattananond (THA) 68-66, Victor Dubuisson (FRA) 69-65, Ross Fisher (ENG) 66-68
135 - Francesco Laporta (ITA) 67-68, Marcus Kinhult (SWE) 67-68, Dustin Johnson (USA) 67-68, Henrik Stenson (SWE) 65-70
136 - Sean Crocker (USA) 68-68, Soren Kjeldsen (DEN) 67-69, Shane Lowry (IRL) 69-67, Phil Mickelson (USA) 66-70, Jhonattan Vegas (VEN) 65-71, Justin Walters (RSA) 71-65
137 - Martin Kaymer (GER) 73-64, Sergio Garcia (ESP) 69-68, Richard McEvoy (ENG) 69-68, James Morrison (ENG) 69-68, Wu Ashun (PRC) 71-66, Thomas Pieters (BEL) 70-67, David Howell (ENG) 68-69, Alexander Bjork (SWE) 68-69, Andy Sullivan (ENG) 66-71, Aaron Rai (ENG) 66-71, Pablo Larrazabal (ESP) 69-68, Jeff Winther (DEN) 69-68, Sebastian Garcia Rodriguez (ESP) 67-70
139 - Brooks Koepka (USA) 70-69
140 - Ian Poulter (ENG) 72-68
141 - Ernie Els (RSA) 72-69
143 - Bernd Wiesberger (AUT) 75-68, Patrick Reed (USA) 73-70, Lee Westwood (ENG) 70-73