Defending champion Toni Bou - Repsol Honda continues his quest for an incredible twelfth consecutive World crown this coming weekend at TrialGP Portugal, round four of the 2018 FIM Trial World Championship.

Back on the calendar after a two-year break, TrialGP Portugal returns to the small town of Gouveia on the edge of the beautiful Serra da Estrela Natural Park for the first time since 2004. Huge, imposing boulders will feature heavily and riders will need to demonstrate courage and technique in equal measure.

Bou has never been lacking in either quality and the thirty-one-year-old Spaniard's abundance of both carried him to a narrow, nerve-racking victory last weekend at TrialGP Andorra with the result decided on the very last section of the Trial. It is almost as tight in the championship chase too with Bou leading by just seven points as his compatriots and Gas Gas team-mates Jeroni Fajardo and Jaime Busto snap at his heels in what is shaping up to be the closest title fight for years.

Last year Bou failed to win just twice, but already this season he has been defeated on two occasions. Whether this is a result of lost preparation time following his back injury in February or because both Fajardo and Busto have raised their game remains to be seen, but what is certain is that Gas Gas were inspired to sign the pair for 2018.

Fajardo was the first to strike on day one at TrialGP Japan with Busto following suit the very next day. The result left Bou looking vulnerable for the first time in a very long time and if Fajardo had not collected a maximum on the final section of TrialGP Andorra he would have taken his second win of the year and now be leading the series.

"It was a lack of attention," explains thirty-three-year-old Fajardo. "I did not give enough importance to the exit of the section and it was very expensive, but I have learned my lesson and now I am even more prepared."

At just twenty years old, Busto is by far the youngest and least experienced of the trio. It is perhaps only the impetuosity of youth that places him third in the championship, two points adrift of Fajardo, after slipping to fifth on day one in Japan and fourth in Andorra. A strong second at the opening round in Spain and his victory on day two in Japan underline his brilliance, but consistency is key in any title challenge.

By his own impeccably high standards, veteran Spaniard Adam Raga - TRRS has had a disappointing start to the season. The two-time World Champion has finished runner-up to Bou every year since 2007, but is currently only fourth in the standings and is already sixteen points behind his great adversary.

On the subject of veteran Spaniards, at thirty-seven Albert Cabestany - Beta is almost two years older than Raga.

After finishing seventh in 2017 - the first time he has dropped out of the World top five in fourteen years - he was considering retirement, but a switch to the Italian manufacturer after thirteen years with Sherco has breathed new life into him.

He finished a stirring second at TrialGP Andorra which lifted him to fifth in the championship, eight points behind Raga, which could be the springboard to a resurgance in his twenty-first season in top-flight Trial.

The first non-Spaniard in the standings is Britain's James Dabill - Beta who lies seventh. The thirty-two-year-old finished a career-best-equalling second on the opening day of TrialGP Japan last season and desperately wants to go one better this year.

Already with a podium finish to his name this season on day one at his home round in Japan, thirty-eight-year-old Takahisa Fujinami - Repsol Honda is the elder statesman of the class. Currently eighth in the championship, this hugely-popular rider was World Champion in 2004 and loves nothing more than launching himself at huge rocks - he has not nicknamed Fujigas for nothing and Portugal could play to his strengths.

The Trial2 class will also be in action in Portugal with seasoned Italian Matteo Grattarola - Honda currently enjoying a commanding eighteen-point lead from Britain's Toby Martyn - Montesa. Grattarola, who was tenth last year in TrialGP, was beaten by Martyn on the opening day in Japan but other than that has an unblemished record this season.

Just three points behind Martyn following his second-placed finish in Andorra, Spain's Gabriel Marcelli - Montesa has a comfortable twelve-point cushion over Britain's Jack Peace - Gas Gas who in turn leads his older brother and team-mate Dan by a further four.

Trial125 completes the line-up for TrialGP Portugal where Britain's Billy Green - Beta is setting the pace. The sixteen-year-old slipped to fifth on the opening day in Japan, but has won every other Trial to open up a thirteen-point advantage over Spain's Martin Riobo - Gas Gas.

Pablo Suarez - Gas Gas from Spain has had three consecutive third-placed finishes to bring himself to within three points of Riobo, but the rider to watch could very well be Eric Miquel - TRRS. Just one point behind his compatriot Suarez, he mounted a strong challenge to Green's supremacy in Andorra and after a disappointing opening round has had back-to-back runner-up finishes to drag himself back into contention.

Follow all the action from TrialGP Portugal as it unfolds over the weekend, with full coverage across all the official TrialGP social media channels, on TrialGP.com plus live qualification on the TrialGP Facebook page.