England's Laurie Canter recorded a five-under 67 to take the second-round lead in Girona on Friday, making four birdies and an eagle before a lone bogey on the 17th hole at the Stadium Course.
Another Englishman James Morrison, with his 71, and South African Oliver Bekker, level-par 72, were a shot behind.
But Antcliff, a stalwart of the European tour who's been struggling of late, put himself in contention with a blistering effort on the home stretch, racking up four birdies in the last eight holes to move into the top 10.
Another Australian Jason Scrivener made it to the weekend on the cut line at two over after a level-par 72, but Scott Hend (76), Wade Ormsby (69) and Zach Murray (80) all missed out.
Canter had been four shots off the lead before shooting the lowest round of the day.
"I love this golf course," the Englishman said. "I love the facilities and everything about it. It's genuinely a bit of a privilege to play it. It's a really special place."
This is the European tour's first time at PGA Catalunya since Miguel Angel Jimenez won the 2014 Spanish Open at age 50 to break his own record as oldest European tour winner.
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