Chris Harris overcame difficult conditions to win his Speedway GP qualification quarter-final at Berwick with a 15-point full house as Sam Masters, of Somerset Rebels, won a race-off for second place.
Coventry Bees skipper Harris went into the meeting as firm favourite to triumph, but all 16 riders faced a testing night as the track on the Anglo-Scottish border was lashed by rain for much of the day.
Covers were used on the bends, but, with rain falling during the meeting, conditions became very tough. A track inspection was called after 12 races, but referee Marek Wojaczek allowed the action to continue.
The elements failed to stop the Cornishman from keeping his dream of a place in the 2013 World Championship alive, if he finishes outside the top eight in this year's series.
Under-21 world finalist Masters, an Australian, is also through to the semis after winning a run-off for second with Daniel King after they tied on 12. American international Ryan Fisher, of Plymouth Devils, cruised through on 11 points.
The Rebels' promoter, Debbie Hancock, said: "It is a great achievement by Sam to not only qualify, but to also finish in second place against some high-class riders in what were far from ideal conditions.
"Sam is doing himself and Somerset speedway proud with his performances on the world stage this year."
Three Swindon Robins riders are through to the semi-final stages, after skipper Hans Andersen (nine points) and Troy Batchelor (seven) both scraped through from their qualifier in Tarnow, Poland.
Peter Kildemand (eight) snatched the last qualifying place from his meeting in Gustrow, Germany.
Andersen said: "That was a tough day at the office, but the most important thing was that I got through. Now it's on to the next round."
The riders who qualified will be drawn into the three semi-final meetings at Vojens, Divisov and Lonigo, which take place on June 30.
The top five from each of these will be guaranteed spots in the GP Challenge at the Croatian SGP venue, Gorican, on September 29, when the first three become Grand Prix regulars for 2013.
Scores: 1 Harris 15, 2 Masters 12+3, 3 D King 12+2, 4 Fisher 11, 5 Watt 10, 6 Sundstrom 9, 7 Buczkowski 9, 8 Aarnio 9, 9 Hansen 7, 10 Sanchez 5, 11 Albin 5, 12 Franchetti 4, 13 Van der Steen 4, 14 Ingalls 3, 15 Complin 2, 16 Helfer 2, 17 Kus 2, 18 Ashworth did not ride.
Plymouth Devils suffered two Premier League postponements inside 24 hours.
The Devils had a wasted journey to North Lincolnshire on Friday evening when their match at Scunthorpe was called off because of a waterlogged track, and their home match against Newcastle Diamonds the next evening went the same way.
The next scheduled meeting for Plymouth is a home Premier League match against Sheffield Tigers on Friday.
Somerset Rebels enjoyed a 58-34 home victory over Glasgow Tigers on Friday evening before a 48-42 defeat at Rye House Rockets 24 hours later, both in the Premier League.
The Rebels enjoyed 11 heat victories at Oaktree Arena as they well and truly clawed the Tigers for their biggest home win of the season, Jason Doyle and Sam Masters both being paid for 14 points and reserve Kyle Newman paid 13.
Doyle, Masters and James Wright all won three heats.
After establishing an eight-point lead as early as heat four, they extended it to ten points by the seventh race and 14 points by heat nine after a 5-1 by Wright and Masters. Four laps later, another 5-1 by Alex Davies and Doyle, after a rerun, saw the advantage stretched to 18 points.
A 4-2 by Masters and Kyle Newman gained a 20-point advantage after heat 12, with further 4-2s by first Doyle and Davies and then Wright and Perry establishing a 55-31 advantage going into the last race of the night.
A re-run saw Joe Screen, who top-scored for the Tigers, hold off Wright and Newman for a shared race.
Somerset Rebels: Doyle 13+1 (5), Davies 6 (5), Masters 12+2 (6), Wright 12 (6), rider replacement (Vissing), Perry 5+1 (4), Newman 10+3 (6).
Glasgow Tigers: Screen 15 (5), Mills 6 (5), Grajczonek 4 (3), rider replacement (Sitera), Grieves 4 (4), O'Malley 0 (5), Campton 5+1 (7).
The Rebels climbed to fourth despite losing at Rye House – by restricting the Rockets to a six-point win. Somerset picked up an away match point.
Doyle had four race wins as he top-scored with 14 points while Josh Auty, guesting for Masters, who was on Grand Prix qualification duty at Berwick, had three wins in his total of 13 (paid 14).
Somerset provided ten heat winners thanks to able support from Davies and Perry but Wright failed to register a point and Newman picked up only one.
Matej Zagar is the first name confirmed to appear in the Simon Stead Testimonial Meeting at Swindon's Abbey Stadium on August 16.
The ten-times Slovenian champion will return to Britain to take his place in what promises to be a star-studded line-up. The former GP star is one of the most spectacular riders in the world, and he became a firm favourite with the Swindon fans after a hugely successful spell with the Robins.
The Robins have moved quickly to rearrange their washed-out clash with Wolverhampton for Thursday, June 28. The meeting was postponed on Thursday night, with the Abbey track waterlogged.