Scotland's Grant Forrest had a 67 to join Dean at 13-under 200, one shot ahead of Victor Perez, Joel Girrbach and Jacob Skov Olesen going into the final round.
Jason Scrivener is the only Australian to have made the cut and is in a share of 54th heading into the final round, at even par for the tournament.
Dean won his first European title just six weeks ago in the British Masters. A victory on Sunday would move him well into the top 10 in the Race to Dubai and practically assure the 32-year-old from England a PGA Tour card for 2027.
He was brilliant for much of the third round, piling up eight birdies to take over the lead. But on the par-4 16th, he went bunker-to-bunker, came up short of the green, chipped too strong and missed a 15-foot putt to make double bogey. Then, he went long on the par-3 17th for another bogey.
But he saved himself at the end with a birdie to share the 54-hole lead.
"It gave a little bit of hope after those previous two holes," Dean said. "But nothing's guaranteed in this game and it only takes a slight lapse in concentration or a bad shot and before you know it you're chasing. It's nice to finish with a birdie on the last. We'll go again and see what happens."
Eugenio Chacarra, who is playing with a foot injury after banging his toe in the middle of the night, had a 70 and was five shots behind. Chacarra is trying to overtake American Patrick Reed for the lead in the Race to Dubai. Reed missed the 36-hole cut on Friday.
