Producing season’s-best performances in the 100m hurdles and high jump, she led Thiam by just 24 points, with 33 points separating the three pre-competition gold medal favourites.
The shot put represents one of Johnson-Thompson’s weaker disciplines but she displayed her gold-medal credentials by launching the best throw of her life to ensure she would limit her losses to superior thrower Thiam.
The 29-year-old Thiam edged ahead by matching her personal best with an unmatched 15.54m.
But Johnson-Thompson, in the event which brought a heartbreaking end to her podium bid in Tokyo three years ago, finished the opening day strongly to reclaim top spot.
On her brilliant effort in the shot put, Johnson-Thompson said: “That was entirely for Denise Lewis sitting in the BBC studio.
“Probably the best thing I’ve ever done in my career – and I’ve jumped 1.98m [for high jump]. That topped everything. A little 14m shot put.
“I’m in really good 200m shape so that was really frustrating. I was aiming for as close to 23 seconds as possible but it’s the heptathlon, [I was] very tired at the end of the first day so I’ll take it.”
The reigning world champion called her second global heptathlon triumph in Budapest last year “the best day of my life”, having completed a remarkable turnaround in her career.
Following the maiden global success in 2019, Johnson-Thompson overcame a career-threatening Achilles rupture only to suffer injury heartbreak in the 200m at the Tokyo Olympics.
Last year, in the absence of the injured Thiam, she took world gold ahead of Hall to set herself up perfectly for the chance in Paris to at last claim an Olympic medal.