And after carding five birdies and two bogeys in his first 14 holes, Masters champion Sergio Garcia picked up further shots at the 15th and 17th to also complete a round of 67 to join Bland at the summit on 13 under par.
The Argentinian was playing on a sponsor's invite in Munich and had slipped to 837th in the world since his last victory at the 2008 Zurich Classic of New Orleans.
In Hartford, Connecticut, Jordan Spieth birdied three of the last four holes, including the last with a dramatic 20-foot putt, to grab a one-stroke lead after Saturday's third round of the PGA Travelers Championship.
But Romero composed himself to rattle in the birdie chance which gave him the outright clubhouse lead ahead of Detry, who had stormed to the turn in 31 but missed a number of crucial chances on the back nine as he closed with a 66.
He left his eagle putt on the last a long way short but held his nerve to make a birdie, leaving the final pairing of Bland and Garcia both needing finishing eagles to force a play-off.
Detry posted a closing 66 to set the target at 16 under but when Garcia three-putted the 16th and Bland missed the green on the next, the door was open for Romero.
"I think it was a good, solid day", Garcia told Europeantour.com. "We've got to go out there, play well again and see if we can pull it off". Spaniard Garcia, in his first appearance in Europe since his first major triumph in April, had started the day as joint leader along with Bland.
In-form Englishman Tommy Fleetwood finished four shots behind Romero on -13, alongside Renato Paratore of Italy, while Sweden's Rikard Karlberg was just above them on the final leaderboard on -14. "I've not been playing that great". I was very happy to see some of the shots I hit and some of the putts I made and very happy with my six under.