Jody Cundy and Katie Toft both won gold for Great Britain on the opening day at the Para-cycling Track World Championships in Brazil.
Cundy became world champion for the 14th time by winning the men's C4 1km time trial to remain unbeaten in world kilometre events since 2006.
The 39-year-old clocked one minute 04.579 seconds to beat Slovakia's Jozef Metelka by almost three seconds.
Toft claimed gold in the women's C1 individual pursuit.
She came home in 4:41.945 to seal victory over China's Li Jieli having overtaken her opponent.
Great Britain clinched five medals in total on the first day in Rio de Janeiro.
Megan Giglia claimed silver in the women's C3 individual pursuit, losing out on gold to Germany's Denise Schindler in the final.
Jon-Allan Butterworth and Blaine Hunt secured silver and bronze respectively in the men's C5 1km time trial.
Crystal Lane-Wright just missed out on the podium on her track return, finishing fourth in the women's C5 500m time trial.