Vanthoor, driving the KCMG Porsche 911 GT3R, was locked in battle with Jaminet's identical Pfaff Motorsport example during the final two hours of the IMSA SportsCar Championship season-opener, the pair rarely running more than half a second apart .
Having led on the penultimate lap after depriving Jaminet of the lead, Vanthoor was then repassed by the Frenchman on the final tour and attempted to regain the lead as they approached the newly-renamed Le Mans Chicane.
The move failed to come off and the blue KCMG car - making a one-off appearance in IMSA - skated through the grass, rejoining the track sideways.
As Jaminet held on to win alongside Matt Campbell and Felipe Nasr, Vanthoor also lost out on second place to the Risi Competizione Ferrari 488, having to settle for third in the car he shared with Patrick Pilet, Dennis Olsen and Alexandre Imperatori.
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Vanthoor, who won the GTD class title last year with Pfaff, admitted afterward that he cried with frustration on his slowing-down lap, but posted a statement to social media on Monday saying he bore no ill-feeling towards Jaminet.
Explaining that he was “still absolutely gutted”, Vanthoor wrote: “I drove my heart out and tried everything I could, but unfortunately it was not enough.
“The movie keeps on playing in my head but there is no rewind button.
“A victory was the one and only thing we wanted, anything else would have been defeat. That was our approach and the way I raced.
“Opportunities to win big races like these don’t come along very often, so when it does you have to put it all on the line.
“The battle I had with Mathieu was exceptional. I have absolutely zero hard feelings.
“We raced hard, very hard. But both with 100% passion.
“The only thing that gives me joy today is to read all the comments about race fans all over the world, celebrating our fight and describing it as one of the best ever.”
Sebastian Golz, Porsche’s project manager for the Porsche 911 GT3 R, said he was left “speechless” by the marque's display in leading 428 of the 711 laps in GTD Pro and scooping the pro-am GTD class with ,Wright Motorsport’s Porsche.
“We can only emphasise how difficult this race was and the high level of professionalism of the teams running all seven vehicles,” said Golz.
“Victory in the GTD class and first and second in the GTD Pro class! That’s no picnic in a race with 35 GT vehicles. It’s a well-deserved reward for the teams, the drivers and Porsche.”
