Later in the month of July, he won his second career ATP Challenger Tour singles title at the 2022 Open Castilla y León dropping one set the whole week.

[6] In March, Grenier won his fourth career Challenger singles title in Les Franqueses del Vallès, Spain.

[7] Grenier made his ATP Tour singles main draw clay-court debut at the 2023 Grand Prix Hassan II.

128 in the world, Grenier made his Masters 1000 singles main draw debut at the 2023 Mutua Madrid Open by winning two qualifying matches.

Grenier made his French Open singles main draw debut thanks to a wildcard, where he lost in the first round to the unseeded Márton Fucsovics in four sets.

[12] In July, Grenier won his fifth career Challenger singles title in Pozablanco, Spain, defeating Juan Pablo Ficovich in the final.

178, he qualified for the 2024 Australian Open defeating compatriot Giovanni Mpetshi Perricard making his debut at this Major and recorded his first ever win at the tournament over another Frenchman Alexandre Muller.

156, he also entered the main draw of the ATP 500, the 2024 Barcelona Open Banc Sabadell as a lucky loser for a second time at this tournament, after the late withdrawal of defending champion and top seed Carlos Alcaraz.