Fabio Quartararo acknowledged his win at Sunday's Italian Grand Prix did not leave him with a "great feeling" following the death of Moto3 rider Jason Dupasquier.
Swiss rider Dupasquier, 19, was struck by another bike after falling and slid along the track at Mugello in qualifying on Saturday.
It was announced before Sunday's MotoGP race that he had died in hospital from his injuries.
Quartararo became the first rider to win in Mugello after starting from pole position since 2014, extending his lead over Johann Zarco at the top of the championship standings to 24 points with six races completed.
Quartararo was in no mood to celebrate, though, the 22-year-old revealing he thought about Dupasquier every time he went past the part of the course where the fatal incident happened.
"Strange, strange day," Quartararo told reporters. "Honestly, there were a lot of emotions before starting the race.
"I get emotional really fast in every condition, so to start the race during that one minute of silence was really difficult and every time I crossed turn nine, I was thinking about Jason.
"This one is for him. It's not a great feeling. You achieve a win, but we lose one of our friends. So, it's not easy."
Meanwhile, Marc Marquez's hopes of securing a strong result in his fourth race since returning from a broken arm were ended at turn three on the second lap when he made contact with Brad Binder.
Marquez accepted responsibility for his early exit and said he is looking forward to getting his season back on track at the Barcelona-Catalunya circuit next weekend.
"If someone is to blame it is me because he was coming from behind," he told DAZN. "I tried to overtake him on turn two. Several riders from the lane have fallen in that chicane.
"I was going to one side and he was coming to the other and he closed in front of me. Fortunately, I fell by myself.
"We have taken a little step this weekend. We have understood several things and we are lucky that next week we will be running again. I have not completed 23 laps at Mugello and I want to see if I can continue with my progression."