In contrast to Ewan's troubles, Spratt's win continues her outstanding form after the best year of the 31-year-old's career.
The Mitchelton-Scott leader won road race silver in September at the world championships.
The expectation was that she would be a support rider for Lexus Blackburn All-Stars teammate Chloe Hosking at the Bay Crits, given Hosking is one of the best sprinters in the women's field.
But Spratt had other ideas on Tuesday and had only her third win in 13 years at the Bay Crits.
“I’m really, really happy, it’s always the first race of the season and you’re not really sure how you’re going to go, but I was pleasantly surprised," Spratt said. "I had a really good, uninterrupted pre-season of training and I’m very happy with where I’m at.
“I was suffering out there, it wasn’t easy. I actually thought this course might be easier than the other way, but it’s harder. When I got away with Peta [Mullins] I know she’s a faster sprinter, so I didn’t want to take her to the line. I just had to keep attacking her on the climb.”
In the men's race, it was an international shoot-out with Austrian Marco Haller (Katusha-Alpecin) getting the better of a five-man breakaway that included German Raphael Freienstein (Lexus of Blackburn) who finished second and Australian's Miles Scotson (FDJ-Groupama), third.
The Lexus Blackburn Bay Criterium Series podium with Raphael Freienstein (L) Marco Haller (C) and Australian's Miles Scotson. (Con Chronis) Source: Con Chronis
"I didn’t really know where I was at since I missed pretty much the whole last season due a severe injury," Haller said.
"This basically was my first competitive race since my injury so, therefore, I’m very very happy to start it in this way.
"I had an incident with a car in training so I had a fracture of the left patella, it took me two surgeries and 190 days to come back on the bike. My career was in danger so I’m very happy to be back"
The hot favourite in the men's race, Ewan's dramas dominated the men's race after the top drawcard of the series pulled into the pits about 20 minutes into the one-hour elite men's race, reporting a tight head stem and a dropped seat post to race officials.
But head commissaire Karen O'Callaghan explained that under cycling rules, they were not mechanical mishaps.
That meant Ewan could not receive a free lap while his problems were fixed, meaning he was out of contention.
"I didn't exactly understand what the rules were, so I thought if you had a mechanical you could go to the pits," Ewan said.
"I hit a bump and my seat dropped down, so I couldn't really ride on it, so I pulled into the pits to put my seat back up.
"Then I thought they said I wasn't allowed to sprint, but apparently I wasn't allowed to go on the front at all. I don't know."
Spratt and Haller will take their ownership of the Lexus Blackburn General Classification and the Gatorade Sprint Ace jerseys into race two of the event which will be live on the Cycling Central Facebook page from 5pm AEDT on Wednesday.
