Jason Doyle starts his defence of the World Speedway Championship when the 2018 Speedway Grand Prix series opens on 12 May, with the first round to be staged at the National Stadium in the Polish capital of Warsaw.

Doyle is one of five previous champions among the 15 permanent participants – Greg Hancock, Nicki Pedersen, Tai Woffinden and fellow Aussie Chris Holder being the others.

If there is to be a new name added to the honour roll of champions by the end of the year the major contenders appear to be Polish, or Russian, with Patryk Dudek, Maciej Janowski and Bartosz Zmarzlik, plus Emil Sayfutdinov looming as serious threats.

Swede Fredrik Lindgren has been the stand-out in early season Polish League matches but shouldn’t rate as any more than a spoiler again this year. Triple champion Nicki Pedersen started the 2018 season off well after missing most of last season, but a hand injury suffered last month has put a question mark over his chances in Warsaw.

Definitely missing the opening two rounds will be Martin Vaculik, who will be replaced by first reserve Niels-Kristian Iversen, after the Slovakian broke his ankle in his first meeting in the UK this season leading to two operations to repair the damage, followed by a skin graft.

Neither Latvia nor Australia are on the schedule this year, so it will be just a 10-round competition to find the champion for 2018.

By Peter Baker