Davis was on the brink of making a painful exit from the Betfred.com World Championship, trailing 12-4 to the man who has made a cruel habit of humiliating him on his favourite stage. Robertson looked set to go through with a session to spare but still needs one more frame after Davis took the last two of the evening to postpone what is surely an inevitable defeat.
The 52-year-old Davis brought this tournament to life and won himself a new generation of supporters with his remarkable second-round victory against defending champion John Higgins. It was tempting, and romantic, to believe amid the euphoria and the scale of his achievement that Davis might have rediscovered the form to take him all the way to the final, 21 years after the last of his six world titles.
But Davis warned he would be taking each ball and each frame as they came, rather than looking further ahead. And in Robertson he met an Australian who potted ball after ball, winning frame after frame.
The 28-year-old from Melbourne showed Davis no mercy in the first round last year and repeated the treatment. Davis gave another sell-out Crucible crowd a classic century to savour in the evening session, an immaculate 128, but that was out of keeping with the flow of the match.
Robertson raced into a 7-1 lead in the morning session and converted that into his emphatic overnight lead. The evening interval score of 10-2 had a familiar look, given that Robertson crushed Davis by the same margin 12 months ago.
The opportunity was there for Robertson to earn himself an unexpected day off, and that seemed likely when he edged their first frame back and then made it 12-2 with a sparkling 92 break.
Davis won the next frame on the black with a gutsy 32 clearance, and then crept over the line in the next, eventually potting the pink after a safety battle. Robertson has every chance of becoming the first man from outside the British Isles to land the world title since Canada's Cliff Thorburn in 1980.
Scotland's Graeme Dott fought back to move on to level terms with Northern Ireland's Mark Allen at 8-8. Allen had led 4-0 and 5-3 after a break of 100 in the eighth frame. But 2006 champion Dott had runs of 74, 116, 85 and 67 in the second session of a match, which concludes this morning.
Earlier, Mark Selby had let Ronnie O'Sullivan off the hook as an intriguing first session finished all square at 4-4.
At one stage in frame three O'Sullivan sat in the front row with journalists while Selby played a shot, to the amusement of the audience, and then he left his seat to watch events on the other table for several minutes, peering around the curtain to check on Ali Carter and Shaun Murphy.
The match O'Sullivan was taking an interest in showed a 5-3 lead for Murphy after the opening session.