Oscar Piastri described the outcome of the Qatar Grand Prix as "painful" after a McLaren strategy blunder cost him a crucial victory ahead of the season finale in Abu Dhabi next weekend.
Piastri is still in contention for the title, but his chances were reduced significantly by finishing second to Max Verstappen in Qatar.
The Australian is now 16 points adrift of McLaren teammate and championship leader Lando Norris in the standings, while Verstappen is just 12 points behind Norris.
After winning Saturday's sprint race and taking pole position in Qatar, Piastri was leading the Sunday's grand prix when an early safety car presented an opportunity to make one of two mandatory pit stops with minimal time loss.
McLaren was the only team not to pit under the safety car, meaning both Piastri and Norris were at a disadvantage versus Verstappen for the rest of the race.
Asked to describe his level of frustration at Sunday's result, Piastri said: "Pretty high. And I think that's saying quite a lot, given the last few races I've had.
"Yeah, clearly we didn't get it right today, which is a shame, because the whole weekend went very, very well. We had a lot of pace.
"I felt like I drove well. So yeah, it's pretty painful."
The missed opportunity came just one week on from Piastri and Norris both being disqualified from the Las Vegas Grand Prix over a technical infringement, but the Australian said the loss of the Qatar victory hurt more.
"I think on a personal level, I feel like I've lost a win today," he said. "In Vegas, I lost a P4.
"Obviously for the team, it's a pretty painful weekend. But yeah, I think yeah, for me personally, this probably hurts more."
Piastri revealed that he questioned the team over whether it should pit under the safety car, but ultimately had to put his trust in the decision of the McLaren pit wall.
"I asked what are we doing, because we were getting close to pit entry and I hadn't had a call yet," he said. "I think when you don't get a call instantly when the safety car comes out, there's probably some discussions going on about what to do.
"In that situation, you have to trust the team, because they have a lot more information than the driver in the car and where gaps are, and stuff like that. So yeah, in that scenario, I have to trust what the team decides."