Lockerbie had back-to-back birdies at the 16th and 17th holes before stumbling to his closing bogey and posting a 3-under 69 at Laguna National's Masters Course.
'It was a pity about the 18th, but I would definitely have taken being tied for the lead after today,' he said.
Playing in the same threesome, Liang, one of two first-round leaders, birdied the 18th to finish off a 4-under 68 and join Lockerbie at 12-under-par 204.
Neither player has ever won on the European Tour.
Indeed, neither had ever held a 54-hole lead before Saturday.
'It is a bit of a new experience but I'm sure I'll be fine,' said Lockerbie, who ended with seven birdies, two bogeys and a double-bogey. 'I'll just try to get off to a steady start and not try to do anything fancy because I don't think it is going to be a really low score which wins tomorrow.'
Second-round leader Jyoti Randhawa of India had an even-par 72 and fell back to third place at 11-under 205 overall, but will join the leaders in Sunday's final group.
Ireland's Peter Lawrie (70) and Malaysia's Iain Steel (71) share fourth place at 10-under 206. Englishman Simon Dyson (67) and Thailand's Thongchai Jaidee (69) are a shot further back at 207.
Steel held an early two-shot lead after opening his round with four consecutive birdies. He battled with Randhawa for the lead late in the round, but both fell back with costly bogeys.
'I dropped a few shots which I shouldn't have, but I am pleased to just be one shot off the lead and still having a chance going into tomorrow,' said Randhawa.
Last year's runner-up and the 2005 champion, Nick Dougherty, fired a 6-under 66 to climb from 54th place overnight into a tie for eighth with Terry Pilkadaris (67) at 8-under 208.
Francesco Molinari (70) and Robert Rock (68) are a shot further back at 209.