Frenchman came through tough matches with Lukas Krpalek and Hisayoshi Harasawa to extend his unbeaten run to 148 judo bouts.
Judo king Teddy Riner had to dig deep to claim victory on his comeback at the Montreal Grand Prix.
The Frenchman needed Golden Score time to beat Hisayoshi Harasawa in a rematch of the Rio 2016 final and take his winning streak to 148 bouts since September 2010.
Riner, 30, had last fought in November 2017 in Marrakech, Morocco, where he claimed his 12th global title at the World Openweight Championships.
And he was severely tested by Harasawa, and Rio -100kg champion Lukas Krpalek who also took him to extra time.
"It was no easy comeback. 18 months is a long time. Today I won but I competed against some fine opponents. It was no walk in the park." - Teddy Riner speaking in the mixed zone after his Montreal Grand Prix victory
Riner was the main attraction in Montreal and lived up to his billing with comfortable wins by ippon against Ajax Tadehara of the United States and Romania's Vladut Simionescu to reach the semi-finals.
Then came an eagerly awaited first meeting between Riner and Krpalek.
The Czech moved up to the heaviest division in 2017 and once told CNN, "Riner has it all worked out, physically and technically. He has no real weaknesses. But definitely I would like to take him on, and try to defeat him."
Despite a considerable weight disadvantage, Krpalek gave Riner plenty to think about with neither man able to score in regulation time.
Riner was handed a first shido early on before both men were penalised for avoiding the grip just after the midway point of the four-minute contest.
Krpalek was dismayed at being handed a second shido 13 seconds from time which left both men one infringement away from disqualification in extra time.
And it was the double Olympic champion who came through 1:56 into Golden Score with a sweeping hip throw (Harai-goshi) for wazari and victory.
There was a hug of genuine mutual respect afterwards with Riner really tested by the man who may well be his biggest threat to a third Olympic title at Tokyo 2020.
"I train with him often at the Olympic Training Camps. He’s a fine judoka. I knew that it was going to be a very difficult bout. I’m aware there is still much work to do to reach my goals for 2020." - Teddy Riner on Lukas Krpalek
It was a similar story in the final with Riner's old rival Harasawa dictating the pace of the contest.
'Big Ted' seemed unperturbed about being issued his first shido after just 47 seconds as Harasawa started aggressively.
The Japanese, who turned 27 last week, was penalised just after the midway point with even the heavily pro-Riner Quebec crowd voicing their disapproval at the decision.
Harasawa was then handed a second shido for passivity before attempting an audacious throw with just under a minute remaining.
His opponent's sheer weight and size made that an unlikely proposition although Riner did receive his second shido which left both men walking the tightrope of disqualification.
Having been content to push forward without launching constructive attacks, Riner just missed out with a sweep throw 19 seconds from time.
Golden Score was required again, and it was the crowd favourite who delivered 1:08 into it with an O-Soto Gari which stood for wazari after a video review.
After another warm embrace, Riner acknowledged the crowd who rose as one to salute their hero.
While it was a victorious return for the sport's most recognisable figure, he knows he has plenty of do if he is to retain his Olympic title.
He said, "This was a tournament, not an Olympic final. Nevertheless, Harasawa is a strong opponent and he is very quick. He was eager to get those Olympic qualification points.
"I have another year to prepare for Tokyo 2020. In two days, I’ll start training again towards my goal in 2020." - Teddy Riner after winning the Montreal Grand Prix
When asked when his next competitive appearance would be, Riner replied, "I'm back now. We will see."