(Reuters) -Ducati's Marc Marquez won his fourth straight sprint of the season at the Qatar Grand Prix to retake the lead in the MotoGP riders' championship while his younger brother Alex of Gresini Racing took second place yet again on Saturday.

The two brothers have finished first and second in each of the four sprints this season as Marc, who led from start to finish, moved up to 98 points while Alex is two points behind.