But Jerome Drayton's elusive 39-year-old mark survived yet another race, as Gillis fell barely a minute short of the record at the 2014 Scotiabank Toronto Waterfront Marathon.
The 34-year-old from Antigonish, N.S., crossed in two hours 11 minutes 20.7 seconds, to finish as the top Canadian and ninth overall.
It was a personal best by seven seconds, but still short of Drayton's mark of 2:10.09 set way back in 1975.
"I'm not too disappointed, I think I was a little fitter than I showed today," Gillis said. "But that being said, one of my big goals was to have a personal best, show to myself that I did have a good buildup. So that's something to take away.
"Only to be seven seconds faster though. . . it's like 'Oooohhh.' I thought I was quite a bit faster," he added.
Laban Korir of Kenya won the men's race covering the 42.195-kilometre through the streets of Toronto in 2:08.14.1.
Mulu Seboka of Ethiopia won the women's race in 2:23:15.
Lanni Marchant of London, Ont., was the top Canadian woman at 2:31.06, seventh overall.
Gillis, who was 22nd in the London Olympic marathon, paced the national record through most of the race, creating a buzz on social media. But he said the chilly weather — the temperature was 3 C when the starter's horn blew — and the wind took a toll over the final seven kilometres.
"The quads just got really heavy out there, and I just couldn't run well on heavy quads," said Gillis, who was greeted at the finish line by his wife Emily Hurst and four-year-old daughter Heidi.
"I would have had to run quick the last 7K. But the quads. . .they were hurting."
Gillis went into this marathon healthier and happier with his running than he's been in a long time, and said the race was a good gauge of where he's at heading into the qualifying period for the 2016 Rio Olympics.
"Even if the time wasn't close today, I feel like I'm getting closer to the goals that I have, like making Rio, this is a big step in the right direction," he said.
"Healthy is a huge thing. Enjoying it and having my family behind me for the next couple of years. And I'm starting to appreciate it more, doing this at 34. To be able to go out and run a personal best, I'd better not be too disappointed."
Marchant was also on pace to lower her own Canadian women's record of 2:28.00 she set at the Toronto Waterfront race last year. But the 30-year-old ran into trouble about the halfway point when her problematic calf muscles cramped. The left one went first, then the right.
"If you watch the footage, you can see my whole left side kind of starts doing its own wonky thing," Marchant said. "That's marathoning. It's not always pretty."
Marchant had said if a Canadian record wasn't in the cards Sunday, she wanted to at least have a positive experience in Toronto.
"It was (positive) until the last 4K," she said. "That last 4K wasn't fun, but by then I already knew I was off record pace which was fine, but by then my quads were done as well, and I think that was just the result of everything, the wind, the cold, compensating for my calves," said Marchant, who's a criminal lawyer in Tennessee.
"Last 4K wasn't the most fun, but by then you've gone so far, so what am I going to do, drop out with 4K to go? We all know I tend not to drop out, when I probably should sometimes," she added laughing.
Marchant praised the crowd that turned out to cheer on the runners. They were packed at least a dozen deep along the final stretch up Bay Street.
"Tons of people cheering, even when I probably didn't look very good going by them," she said, laughing.