While their leading rivals had to compete with a dodgy hip or a sliced knee, Wenjing and Cong avoided any visible mishaps to earn 81.23 points for their 'Blues for Klook' short skate.
The silver medallists at the worlds behind Meagan Duhamel and Eric Radford for the last two years will take a narrow 1.39-point lead over Germany's Aliona Savchenko and Bruno Massot into Thursday's free skate.
A hip-muscle injury that Radford has struggled to shake off for over a week forced the Canadians into an 11th-hour rejig of their programme -- with the pair replacing their side-by-side triple Lutz with a triple toeloop.
That gamble partially paid off as Radford managed to touch down on his feet following the jump, albeit with a snatched landing.
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A hand down by Duhamel on the throw triple Lutz incurred a deduction but it was in the side-by-side spin that Radford's hip really played up as he went completely out of sync with his partner.
Duhamel ended the botched performance to Seal's 'Killer' by raising a clenched fist to the heavens above but that failed to sway the judges and a score of 72.67 left them adrift in seventh place.
"I've never gone out not knowing if I'm going to be able to finish the programme," Radford said through a coughing fit.
"My hip has been massaged to death. I am taking pain killers that I am allowed to. It still doesn't feel 100 percent."
His partner added: "I think we did great and I'm a little sad the panel didn't agree with us.
"We hadn't tried a side-by-side triple toe until today since the first week of December. I don't know anyone else that cannot train a jump for three months and go out and do it at the world championships."
Russians Evgenia Tarasova and Vladimir Morozov did not even know if they would make it on to the ice after Morozov’s skate sliced into Tarasova’s knee during Wednesday's morning practice.
A few stitches later, the European champions were ready to conquer the world. A messy landing on the throw trip loop and an out-of-sync spin narrowly denied them a place on the top of the leaderboard as they finished third, trailing the Germans by less than half a point.
"We were thinking about withdrawing because after this incident... we didn't know how I would feel in skates. But when I was asked 'will you skate?', I said 'I will'," said Tarasova.
Morozov added: "It was hard for me, I was worrying about my partner even more than she was. It was totally her decision to skate. She is a hero for all our country and for me."
(Reporting by Pritha Sarkar, editing by Toby Davis)
