The Dutchman narrowly missed out on making the European Ryder Cup team in 2014, finishing in the top 50 on the European Tour rankings for eight consecutive seasons between 2010 and 2017.
He won his sixth title in 2018 but is relying on a career earnings exemption this season after finishing 126th last year and losing his playing privileges.
He has bounced back in some style, with three top-threes so far in 2023, and will now head into the last 18 holes in Munich on Sunday at 14 under, three shots ahead of countryman Daan Huizing.
“Today was pretty much flawless,” he said after his round on Saturday.
“I didn’t get into trouble that much and if I did miss the fairway I hit a great shot and still created a birdie chance. I made some nice birdies coming down the last four or five holes.
“We’ve got another 18 holes here and I’ve got to keep a cool head. I’ve got to hit some shots like I did today and we’ll see what happens tomorrow but I’ve got to try and play shot-by-shot, like I did today, and if I do that I’ll see if it’s good enough.”
Kiwi Daniel Hillier entered the day with a one-shot lead and had extended that to two at the turn but he found water on the 11th and tee trouble on the 13th before three-putting to leave the door open to the field.
Luiten was the man to take advantage, making seven birdies – including four in his last six holes – and no bogeys to match his lowest round of the season.
Huizing signed for a 66 to sit at 11 under, a shot clear of Hillier, Ryder Cup vice captain Edoardo Molinari and South African Thriston Lawrence.
England’s Daniel Gavins was at seven under, one ahead of countryman Richard Mansell and Scottish duo Calum Hill and Connor Syme, the latter of whom made a hole-in-one at the second in his 68.