In contrast, Australian hope Anthony Quayle headed in the opposite direction. Starting the day one shot off the lead, he carded an 80 that dropped him to one over par, leaving him the wrong side of the cut.
Senior, 37, still searching for his first DP World Tour victory in his 151st event, had five birdies and an eagle in the best round of the day at Golfclub Munchen Eichenried.
That put him into a three-way tie with South African Michael Hollick (68) and Mexico's Carlos Ortiz (67), one behind another South African, Hennie du Plessis, who eagled the last to snatch the outright lead.
English duo Joe Dean and Paul Waring were in a group on nine under, but the latter looked to be making a bid for the lead after four birdies in seven holes from the sixth, only to manage five pars and a bogey coming home to card a three-under 69 to match his compatriot.
They were level with American YouTuber Brad Dalke, who recently left Good Good Golf, which has 2.1 million followers, to spend more time with his family, who shot a 66.
Dalke, a former US Amateur runner-up, received a sponsor invitation to make his DP World Tour debut, his first appearance in a world-ranked tournament since the Korn Ferry Tour six years ago.
"There's a lot of YouTube fans and they love watching me and they vouch for me, so I'm trying to prove for them as well," he said.
Three other Aussies also missed the projected cut. Jack Buchanan and Jason Scrivener were three under after posting 71s, while David Micheluzzi finished alongside Quayle on one over.
12°C