The 2011 Masters winner appeared to have recovered from the rib injury that has affected his swing for much of the season and was on 14-under-par 130 after 36 bogey-free holes in the $1-million Asian Tour event.
Indian-born Swede Daniel Chopra had his second successive 67 to lie four shots behind Schwartzel before second-round play was suspended due to darkness.
Twenty-five players will return early on Saturday to finish their rounds.
After a 90-minute delay due to a lightning storm, last year's runner-up Schwartzel rushed to the 18th tee box to complete his round in semi-darkness to earn a few precious extra hours in bed on Saturday.
"We were running to finish. I didn't want to come back at 5 a.m. to play one hole - (I'm) happy to have a bit of a sleep," the 28-year-old South African said.
"It has been really solid. I've put two great rounds together. I hit the ball nicely and gave myself a lot of chances.
"It is still a long way to go. It's half the job done. From my side, I just have to keep playing."
Asian Tour rookie Masanori Kobayashi of Japan briefly held the lead before signing for a five-under-par 67 to drop five shots off the lead.
Sergio Garcia was three shots further back with big-hitting Scott Hend of Australia after the Spaniard carded his second straight 69.
Garcia turned in 36 but bounced back with three birdies in the closing five holes.
"I'm in a decent position. I would like to do better for the weekend but hopefully if I get a good weekend then I might have a chance," said Garcia.
Joining him on 138 was Masters champion Bubba Watson who sank three birdies in his opening eight holes but could not keep the momentum going and settled for a two-under-par 70.
Defending champion Lee Westwood was left to lament his poor putting after carding a three-under-par 69 to fall nine shots off the lead.
"Just okay, played alright. I wasn't making anything," the world number six said.
"I've made nothing the first two days and left too many out there - missed too many short ones which is the main difference really," said the Englishman. (Reporting by Amlan Chakraborty; editing by Clare Fallon)
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