The 24-year-old has teammate Lando Norris breathing down his neck 14 points behind while Red Bull's resurgent champion Max Verstappen is biting great chunks out of his lead with five rounds remaining.
The pressure is ramping up but Piastri, even if his advantage has slipped away with mistakes creeping in and some frustration emerging on track, has his own narrative.
"Obviously the last few weekends have been a bit tougher than some of the ones, especially at the beginning of the season, but ultimately I still feel good," the Australian told Reuters at the Mexico City Grand Prix.
"Things are tight, things are close, but it's been like that for pretty much the whole season.
"For me, whether the championship lead was one point or whether it was 50, it's ultimately not going to change what I'm here to try and do."
Piastri has been beaten by Norris in the last four races and not won since the Netherlands at the end of August, when Verstappen was 104 points behind. The four-times world champion has since closed the gap to 40.
If some fear he could be tossing it all away, with the Aussie battler in danger of becoming an Aussie bottler, Piastri is unflustered.
"I know there's people in this fight, I know that it's going to be tight, but I've known that for a very long time," he said.
"The stakes do go up the closer to the end of the season you get and there's more effort that goes into trying to manage it.
"Ultimately if you're fighting for anything worth fighting for, or success on any stage, there's going to be nerves and there's going to be pressure involved."
A wry grin appears when asked about Sky television commentator David Croft comparing him and Norris to the couple in a jeep in the movie Jurassic Park as a rampaging T-Rex, or T-Max, crashes towards them.
"Obviously it's important for the sport to make everything as exciting as possible, the last thing that the media are going to do or especially TV and stuff like that, people promoting Formula One, is make it sound more boring," he said.
"So I very much get that side of things... but ultimately when you remove all of that, it boils down to the same things: A few people driving around the track, trying to beat each other.
"That feeling is the same as the junior championships I had, so I get it. I don't pay much attention to it, some of it is funny, but ultimately it doesn't dictate how I'm going to try and win this championship."
The Australian had a stellar record in junior series, winning three titles in a row at the first attempt while also having to overcome setbacks and pressure.
"Ultimately my experience is there's not one way of winning a championship, they all feel a bit different," he said.
"It's just about trying to do what I can do to win races first, and if I can do that the championship will look as I want it to."
Piastri has won seven times this season, more than any Australian in one F1 campaign, and is well aware of what a title would mean for a country that last had a champion with Alan Jones in 1980.
But Formula One drivers are selfish animals and Piastri makes no bones about his main motivation.
"Whether it was 45 years ago, or whether it was last year, that doesn't really change anything for me," he said.
"I'm just trying to do what I can, because ultimately F1 drivers want to do things for ourselves and the history of that is a bonus for me."