The financial boost is significant for Samuel and Gill, whose career earnings stood at 118,300 pounds and 154,000 pounds respectively before the tournament.
Other British players faced setbacks: Jay Clarke lost 6-4, 6-3 to Thomas Faurel, Harriet Dart fell 6-1, 6-4 to Leyre Romero Gormaz, and Jan Choinski withdrew before his match against Pierre-Hugues Herbert.
Former world number four Bianca Andreescu and Karolina Pliskova also exited the qualifying tournament, while former US Open champion Sloane Stephens advanced to the final qualifying round by defeating Italy's Lisa Pigato 6-4, 6-1.
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In a separate tournament, British men's number one Cameron Norrie was eliminated from the Geneva Open after a 6-4, 6-4 second-round loss to Argentina's Mariano Navone.
