The Reds looked on track for the biggest win of their season after a stunning hat-trick from 20-year-old winger Tim Ryan on his starting debut put them 31-20 clear on Saturday night.
But the powerful Blues somehow found an answer, scoring three tries in the last 13 minutes - including one deep into additional time - to sink their rivals 41-34.
Nock was backing up perfectly to find the winning points after winger Caleb Clarke initially broke the line, countering a Reds drive where they looked intent on finding the winning points.
It was the Blues' sixth straight win to sit one point behind the ladder-leading Hurricanes, although the Reds delivered another reminder that their best rugby can challenge the competition's best.
They added the last-gasp defeat to a golden-point loss against the league-leading Hurricanes earlier in the year.
"It's happened with the two top teams in the (competition) ... we're getting closer, we've just got to find a way to knock those guys off," Reds coach Les Kiss told Stan Sport.
Reds coach Les Kiss knows his side can take it up to the best teams in Super Rugby. (Darren England/AAP PHOTOS)
"We went hammer and tongs, we imposed our game on them ... 'nearly' isn't good enough, but they did well.
"They executed pretty well and unfortunately we just weren't good enough to take it at the end, but maybe a call here and there or a better kick here or there maybe changes it.
"But we're not going to go into what-ifs about this, we're just going to build on the positives."
The visitors had only tied the scores on 75 minutes through bench prop Kurt Eklund, with dynamic No.8 Hoskins Sotutu sparking their late rally six minutes earlier.
The late drama overshadowed a breakout game from Junior Wallaby Ryan, with his pure speed creating his second and third tries.
Tim Ryan has scored a hat-trick in his Super Rugby Pacific starting debut, but the Reds fell short. (Darren England/AAP PHOTOS)
He classily capped a scrum set-play for a 24-20 lead, before carving up defender after defender from a standing start to complete his hat-trick and put them 31-20 clear.
He had earlier grabbed their first lead of the contest after an audacious chip-and-chase from centre Hunter Paisami allowed him to be put away.
Alarm bells were ringing early when the Blues powered over twice in the first 19 minutes, with only three missed kicks at goal from five-eighth Harry Plummer keeping the score at 10-0.
But Blues captain Patrick Tuipulotu credited the way the Reds surged back into the contest.
"We respect the Reds and how quick they came back in the second half, they scored some pretty crucial tries," he told Stan Sport.
"We were on the back foot and they really put the pressure on us.
"For us it was about focusing on the next job, trying to get a good kick, pushing that ruck and trying to get the ball back.
'But there were quite a few times the Reds caught us in that area and got us going backwards."
Winger Suliasi Vunivalu's second-half try made up for a lazy put-down that cost him the match's opening points.
He did the hard part, climbing high to gather a bomb above his Blues opponent before using his strength to spin and find the line, only to botch the easy try despite no pressure from defenders.Â
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