Spaniard Jimenez, who is aiming for a hat-trick of victories having won the Hong Kong Open in 2004 and 2007, posted a three-day total of 10-under-par 200 to go atop the leaderboard with overnight leader Campbell (69) at the Hong Kong Golf Club in Fanling.
Teen titan Matteo Manassero of Italy fired an ominous warning to his elder rivals as he charged back into contention with a 64 to share third place with China's Zhang Lian-wei, who will become the third oldest winner on the Asian Tour at 47 years and 171 days if he completes his dream ‘Chinese Slam' on Sunday.
Jiménez, who started his round one back of Campbell, turned in 34 and picked up his first birdie on the 10th hole.
He marked his card with another birdie on the par-five 13th and looked to have snatched the outright lead after Campbell's approach shot found the greenside bunker at the last.
"It was a little boring the first nine holes, no birdies, nothing happened there. But at the end I made a birdie from four metres on the 10th and another on the 13th from about eight metres," said Jimenez.
"I like to be in contention on this golf course and you have to have patience and let everything happen. And that's what's going to happen tomorrow [Sunday], stay patient because anyone can win," said the Spaniard.
Despite chipping his shot well short of the hole, Campbell showed great resolve when he saved par by sinking his putt from 10-feet to stay in the lead.
"Today [Saturday] was sort of a scrappy round. Apart from a couple of drives, it was pretty average really. But once again, I just managed to grind out a score, which is very important to me. I turned a 73 into a 69, which is always nice," said Campbell.
Having gone without a win since lifting the US Open title in 2005, Campbell showed his resurgence by draining a 15-feet birdie putt on the par-four first.
He turned in 33 and mixed one bogey against another birdie to end the day with a 69.
"I've still got a chance to win tomorrow [Sunday]. It would be very satisfying if I can win and finally get some more silverware to add to my trophy cabinet. It would also be a nice little way to finish the year," said the 43-year-old.
Zhang promised to return with renewed vigour as he bids to complete his unique treble, having won the Macau and China Opens previously on the Asian Tour.
The five-time Asian Tour winner started off promisingly with three birdies in his opening four holes.
But he gave those three shots back with successive bogeys starting from the sixth.
"I got a little tense after I three-putted on the sixth. I dropped another on the seventh and hit a poor tee shot on the eighth. After I saved par on the ninth, I told myself to calm down before starting my back-nine," said Zhang.
Zhang then opted for a more conservative approach in his inward-nine and managed to pick up another birdie on the par-five 13th against eight pars.
"I played quite conservatively in my back-nine as I just wanted to give myself a good chance for tomorrow [Sunday]. I've many friends coming over to Hong Kong to support me and hopefully tomorrow [Sunday] I can reward them by finishing the week with a good round," said Zhang.