The Real Saga three-year-old loomed as a big threat at his first start in a Restricted Maiden race over 1200m a month ago, but he could not quite overhaul Ablest Ascend to settle for a close third.
Encouraged by that first run, trainer Young Keah Yong has since kept the Macau-owned galloper ticking over towards his next outing in this Saturday's $75,000 Restricted Maiden race over 1000m on Polytrack, duly picking up the reward despite a late riding change.
With jockey Chin Chee Seng unable to make the 50kgs his three-kilo claim allowed, Young handed the ride to apprentice jockey Iskandar Rosman, who didn't let the golden opportunity go begging.
Settling Young's horse in an ideal spot one-out one-back throughout, Lee Freedman's Malaysian apprentice waited for the right moment to push the button at the 300m as race-leader and favourite Sahabat (Shafrizal Saleh) got collared by Real Efecto (Ruan Maia).
A three-way fight ensued, but it was River Brilliance ($19) who powered home a shade better, outsprinting Sahabat before fending off a stinging late challenge from Strong N Smart (Juan Paul van der Merwe) to prevail by a neck.
Presumably softened up a little by his early hard work to come across from a wide draw, Sahabat still fought on gamely for third place another half-length away. The winning time was 58.26 seconds for the 1000m speed dash.
"On his trials, we knew he had potential and he showed it at his first run," said Young.
"We were expecting a good run today. It's unfortunate for CS Chin, but Iskandar did a good job on the horse.
"Iskandar always listens to instructions, as he's shown in the past when he won on My Dreamliner for us. I had faith in him and that's why I had no hesitation in picking him."
Young was also particularly pleased he had saddled his first winner for Mr Ho Pui Kim, especially after he recently inherited three other runners following the exit of the Macau businessman's former principal trainer Mok Zhan Lun from Kranji, including top galloper River Radiance.
"River Brilliance was with me from Day 1, and now I have three other horses for Mr Ho," said Young who also took over the training of River Roca and River Ruby, who have both already raced for him, albeit without flattering.
"It's great River Brilliance has given us our first winner together, and hopefully, there'll be more to come.
"I'm taking my time with River Radiance. There aren't many races for him at the handicap, I'll probably race him next year.
"I just got him at the stables, and for now, I'm just trying to get him fitter. There is no rush."
A four-time winner by Rip Van Winkle, River Radiance raced four times at Group level, mostly in sprinting events. While he had shown plenty of upsides in the lead-up, the runs had fallen short of expectations, with a fourth place to Nowyousee in the Group 3 New Year Cup (1200m) as his best showing in elite company.
He was tested over the mile in the Group 2 Stewards' Cup but he didn't stay.