Northern Ireland's Jonathan Rea made it five World Superbike wins from five by snatching victory in race one in Spain after Welsh rival Chaz Davies crashed.
Davies had just regained the lead in Aragon when he slid off to leave the way clear for Rea to extend his championship advantage to 47 points.
It is a commanding lead for 30-year-old Rea who is aiming to become the first rider to win three WSB titles in a row.
Italy's Marco Melandri was second in Saturday's race and Tom Sykes third.
Englishman Sykes is Rea's closest rival in the championship standings with Davies now in third.
The second race of the Spanish round takes place on Sunday at 12:00 BST.
|WSB Riders' Championship|
|Jonathan Rea (Gbr)||Kawasaki||125 pts|
|Tom Sykes (Gbr)||Kawasaki||78|
|Chaz Davies (Gbr)||Ducati||70|
|Marco Melandri (Ita)||Ducati||65|
|Alex Lowes (Gbr)||Yamaha||62|
|Jordi Torres (Esp)||BMW||39|