The 19-year-old has two Champions League goals and one Ligue 1 strike to his name in his past six competitive outings, after earning a spot in Laurent Blanc's side due to an injury to Thiago Silva.
The former Brazil Under-17 representative said he has defied his own assessment of his ability, scoring against Olympiakos Piraeus, Toulouse and Benfica.
"I didn't know I could do that. In youth teams, I scored some goals but since I turned pro, be it at Corinthians or Roma, I had never scored," the teenager told Ligue 1.com.
"It's magical what's happening with PSG.
"Right from my first game, despite not having played for four months, I scored my first goal.
"It's a moment I'm going to remember forever. And then, almost straight after, I scored two more important goals."
Marquinhos, formerly of Italian club Roma and Brazilian outfit Corinthians, said Blanc - an ex-defender himself - encourages his stoppers to get forward and impact the scoreboard.
"It's so new for me I didn't know how to celebrate... I was a bit lost," Marquinhos said.
"More than the joy it brings, it also gives me confidence. I needed that.
"He (Blanc) encourages the defenders to go into the opposition box for set-pieces.
"It's something he really wants to develop and which should become our trademark.
"He shows us how we should position ourselves, which runs to make."
Thank you for reading 5 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1