The Craft-Bamboo Racing driver looked to have had his hopes of a second Macau GT triumph dashed yesterday in a dramatic finish to the opening race. Running second, he slipped on oil left by a stricken car on the run to Lisboa and crashed his Mercedes heavily into the wall.
The subsequent red flag meant he was classified second in Race 1, but getting to the grid for Race 2 required a huge overnight repair effort by the Craft-Bamboo crew.
O'Young paid them back in fine style with victory in today's 12-lap finale.
He set up the win by jumping polesiter Ye Hong Li (TORO Racing Porsche) at the start, track position proving critical as he kept the reigning Macau GT Cup winner behind.
O'Young was given a temporary reprieve when the safety car was called on Lap 8, although he then faced his sternest test of the race when it went green just one lap from the finish.
He was up to that test, though, O'Young holding off Ye to add to his 2008 Macau GT Cup crown.
He becomes just the fourth multiple winner of the Macau GT Cup (along with Keita Sawa, Edoardo Mortara and Maro Engel) and just the second, with Mortara, to win it in different brands of car.
"I'm lost for words, to be honest," said O'Young. "We made it onto the grid with 10 seconds to go. If they opened the gate and I didn't make it out, I'm out [of the race]. Literally 10 seconds before we got the car together. The guys worked all through the night. This victory is for them.
"The car is still quite damaged, the chassis is bent. I'm sure the guys behind could see I was struggling a lot. I just tried to control the race. In the hills I didn't push very hard to try and save my tyres and at the bottom I tried to push harder, where they could attack me.
"That's how I ran my race. Maybe the safety car saved me a bit today."
Ye agreed that O'Young was sporting damage in the race, complaining of oil coming from the battered Mercedes.
"Congratulations to Darryl, he did a decent job," said Ye. "The thing is, the whole race his oil kept spraying on my screen. I couldn't see anything towards the end of the race. And also my tyres were covered in oil.
"But I enjoyed the fight with Darryl. He was defending very hard and also it's very difficult to overtake here, there's no space at all."
Luo Kai Luo was a consistent threat throughout the race in his TORO Racing Mercedes, spending the race parked under his teammate's rear wing as he claimed a well-earned third place.
Chen Wei An (Harmony Racing Audi) was in the lead pack for the first eight laps as well before dropping back with a puncture. That elevated Uno Racing Team Aston Martin pair of Marchy Lee Ying Kin and David Pun Kwan Lum to fourth and fifth.
Lin Nan (TORO Racing Mercedes) finished sixth ahead of Liu Qi Ren (Parkview Motor Lamborghini), Lu Zhi Wei (T.K.R Audi), Wong Kwai Wah (SON VENG Racing Team BMW) and Brian Lai Chun Kit (Parkview Motor Lamborghini).
Alexandre Imperatori, meanwhile, made decent headway early after his issue in yesterday's race, but was seemingly struck once again by technical issues in his Meidong Racing Porsche and needed to make an unexpected stop. He was classified 12th.