BBC Sport
Jonathan Rea completed a treble in Qatar to take his final tally of World Superbike wins this season to 17, one more than Spaniard Alvaro Bautista.
Rea followed up his victories in Friday's first feature race and the Superpole race on Saturday by finishing first in the second feature event.
The Kawasaki rider was chased home in race two by Ducati pair Chaz Davies and Bautista, who took second and third.
"It's incredible. What a weekend and what a year," said Rea after race two.
"It's been a dream season and I've achieved a career goal of finishing every single race in the points," added the Northern Irishman.
Rea's total of 2019 race wins equalled the tally he accumulated in 2018 although there were more races held this year because of the introduction of the new 10-lap Superpole sprint events.
Bautista was the early leader of Saturday's main race under the floodlights at the Losail International Circuit in Doha but Rea overhauled him and held off the challenge of Davies and his team-mate to win the final race of the season by three seconds.
Five-time world champion Rea's final winning points margin over Bautista was 165 points.
Former MotoGP rider Bautista was runner-up behind start-to-finish winner Rea in the sprint race, followed by Alex Lowes and Leon Haslam.
Lowes, Toprak Razgatlioglu and Eugene Laverty made up the top six leaderboard in race two.
Rea's triumph in the opening race of the weekend on Friday had clinched a fifth successive manufacturers' championship for Kawasaki.
The Ulsterman is now unbeaten in six races at the Qatar round of the series, having achieved a double in 2017 and a win in the only race held 12 months ago.
2019 WSBK Riders' ChampionshipJonathan Rea (GB)Kawasaki663 ptsAlvaro Bautista (Spa)Ducati498Alex Lowes (GB)Yamaha341Michael van der Mark (Ned)Yamaha327Toprak Razgatlioglu (Tur)Kawasaki315Chaz Davies (GB)Ducati294