It lifted again when she scampered through for a bye five overs later to help her side overhaul Auckland's total of 245 and win the one-day competition for the first time.
It was a moment of utter elation but also relief.
While Blakely was disappointed her team-mate had got out one short of a hundred, the 18-year-old also recognised the weight of responsibility had just shifted to her shoulders.
Bates had guided the side to the cusp of a historic victory and now it was up to teenager to finish the job and the Sparks still needed 37 runs from 5.3 overs with two new batsmen at the crease.
Polly Inglis joined Blakely and the pair added 30 to nudge closer before Inglis was dismissed. Blakely was undefeated on 23 when she and Sarah Osborne ran that bye.
It eclipsed her previous highest score of just three and it was the perfect time to find her feet at the top level.
''It was a great feeling,'' Blakely said.
''I was shaking facing the bowling but it was exciting at the same time. I tried to stay positive when we were so close and I thought we could do it.''
Blakely tried not to look over to where Bates and coach Warren Lees were stationed. The pair were pacing, and Bates was up and down from her seat.
Earlier, Bates had claimed a hat trick and effected the brilliant run-out of opener Victoria Lind.
The dual basketball and cricket international has been to the Olympics with the Tall Ferns and played in three world cup finals with the White Ferns but rated the Otago's first trophy in 51 years as a career highlight.
''I'd have to say that was probably the best feeling I've had after a game,'' Bates said.
''Everything went our way and we played out of our skins. I'd probably put that as a career highlight, just because of the way it felt afterwards.''
As far as getting out one shy of 100, Bates said all the disappointment melted away with that bye.
''To be honest, I didn't realise what I was on when I played the shot that I did. It was a little bit unnecessary. I missed a full toss and obviously I was pretty disappointed after my dismissal.
''But as soon as the final runs were made it didn't mean anything. If I'd had got a hundred and we'd lost, it would have been the worst feeling in the world.
''Just to win and see the younger girls finish the game off was probably the most pleasing thing.''
While Bates' innings provided the backbone of Otago's chase, all-rounder Victoria Abbott also played a starring role.
Like Blakely, she waited until the final to post her highest score, scoring 66 from 94 deliveries and combining in an Otago record fourth-wicket stand with Bates. The pair added 143, surpassing the previous best of 86.
Legspinner Emma Campbell also helped set up the victory with three for 47.
For the senior campaigners like Katey Martin, Sarah Tsukigawa and Bates, the win was kind of a cathartic feeling.
''We've had some pretty dismal performances and there have been lots of highs and lows - and this just makes it all worthwhile,'' Bates said.
''It just shows in one good season that we can compete. Everyone was well aware that we were sort of creating history.''
Otago won the Hallyburton Johnstone Shield in the summer of 1962-63. That was a two-day tournament held over the course of a week.
Auckland had some consolation when it won the twenty20 title yesterday, beating Canterbury by seven wickets.
