World number one Dustin Johnson brought out his major-winning best game before fading light brought an end to day two of the Saudi International.

After an opening three-under-par 67 on Thursday, Johnson upped his level and was five under for his second round through 14 holes, for an eight-under aggregate that put him two shots behind co-leaders Ryan Fox and Stephen Gallacher.

A long birdie putt at the second hole set the tone as Johnson's card remained blemish free, as had also been the case in his opening 18 holes, and he made further gains at the fourth, seventh, 13th and 14th to move firmly into contention.

It put the reigning Masters champion into a four-man tie for third, with plenty of golf in the second round to be completed on Saturday morning.

Local stormy weather caused an interruption of over two hours to the early afternoon action at Royal Greens, where New Zealander Fox managed to complete his round but many could not.

Like Johnson, Gallacher was on the back nine when it became unrealistic for play to continue, the world number 501 from Scotland having followed his dazzling 62 on day one with a steady two-under-par performance through 12 holes.

Fox, ranked 208th in the world, completed a second successive 65 to earn the clubhouse lead, with six birdies and a bogey on his card.

He is determined not to be distracted by the star-studded field at the European Tour event, saying: "This is what you play golf for, to be in contention.

"It's been a while since I've been in this position and I'll just go out and enjoy it on the weekend and see if I can keep playing how I'm playing. I know if I do, I've got a good chance on Sunday.

"I don't know how many of the top 50 in the world are here this week but it's a lot. And there's a reason they're there, they're world-class players, and I certainly hope to be there one day."

Quoted on the tour's website, Fox added: "If I can play well this week, then it's a step forward in that direction."

Johnson was joined on eight under by Englishman Andy Sullivan and Austrian Bernd Wiesberger, who both completed their rounds, plus Sweden's Marcus Kinhult.

Former British Masters winner Kinhult, 24, had a triple bogey at the second but an eagle and four birdies kept him towards the top end of the leaderboard, with two holes of his round left to negotiate.

Tommy Fleetwood and Justin Rose both reached seven under, and that was also the mark where their fellow Englishman David Horsey stood after 12 holes when play ended for the day. The first-round leader made heavier weather of it on Friday as he followed up his opening 61 by producing 10 pars and two bogeys.