Sonka, who began his season with two disqualifications, had arrived for the season's finale at the Texas Motor Speedway in Fort Worth five points behind overall series leader Michael Goulian, who had ended his run of three consecutive victories at last month's race in Indianapolis.

Australia's Matt Hall, runner-up in 2015 and 2016, was just two points behind him.

With 15 points on offer to the winner, all three had everything to play for and when Sonka produced the best qualifying time of the three, finishing second behind 2016 champion Matthias Dolderer of Germany, the pressure appeared to be on the US flyer, who had only managed ninth place.

In the event, Goulian could only manage eighth place in 58.531sec.

Both Hall and Sonka reached the final four round, with the Czech due to race last.

The Australian, flying second from last, produced a hot time of 53.100.

Knowing he had nothing to lose, Sonka went all out on the track and flew the perfect run, posting a 52.796 time which saw him take the win and the 2018 title with it.

He finished with 80 points overall, with Hall earning 75 and Goulian 73.

The nearest challenger to the top three, Mika Brageot of France, totalled 41.

"It's a different story than last season, and it's my biggest sporting achievement," said Sonka.

"Unfortunately, the only thing that I missed was having Mikey [Goulian] in the final four as well, but it was a beautiful race.

"For the last flight I managed to have a clear head.

"I heard that Matt flew a super time and I knew I had to push harder and definitely not do a penalty or mistake, and I managed.

"I cannot be happier."

Hall added: "It was an interesting day.

“We stuck to our gameplan, which was one round at a time.

"I had to beat Martin in the final four and as I had to fly first, I went all out.

"That was as far as I was going to push without getting a penalty.

"To come out with the time I did, it was fast for the day, and to sit in the hold and hear Martin get that time was disappointing, third time second in the world, and once third.

"So four times on the overall podium is a good stat on its own, but to not have won it yet is pretty frustrating."

Goulian added: "We had an engine problem in the round of 14 and it put me in the back, so I had to fly against Martin - and he's been flying fast all week, so we knew we had to go out there and try to win.

"I would've kicked myself if I'd gone out there, flew safely and lost by half a second.

"It's been an amazing year for me and my team and I wouldn't change it at all.

"We'll be back stronger next year."