Pierre Gasly accused Fernando Alonso of mistreating Toro Rosso drivers because of their team's partnership with Honda, while also suggesting the McLaren veteran has become more aggressive on-track since confirming he will leave Formula 1 at the end of the season.
Alonso was in fiery form at the Italian Grand Prix, clashing with Kevin Magnussen in qualifying and then muscling an overtaking Gasly off the track at the early safety car restart at Monza - an incident that was not aired on the F1 world feed.
Gasly went on to be classified 14th after struggling with damage sustained bouncing over the kerbs at the first chicane. Alonso retired with an engine issue.
The Spaniard is set to switch to IndyCar in 2019 and Gasly believes Alonso's standards of decorum may be slipping.
"I think for sure his approach is a bit different because he knows he's not going to be in Formula 1 next year," Gasly said. "Looks like he's even more aggressive than he used to be.
"And yeah, for me today what he did wasn't fair, and we know that if you are alongside you need to give the space of one car, and today he didn't.
"I know he doesn't like us because we have the Honda engine, but nevertheless."
Gasly recalled the incident, saying: "Basically, we came after the safety car into Turn 1 side by side, I went on the outside and he pushed me completely out of the track.
"I tried to stay as on track as much as I could, but he just didn't leave me the space, I had to jump over the kerb and then he also touched me and completely damaged all the right side of my floor.
"[It] was only on the right side so from right to left corner [it] was different.
"I was losing already downforce when I was by myself, but following other cars with the extra loss of downforce, was impossible to really get close. It was a long, long Sunday."