Charley Davison impresses as British trio advance into next round
Four out of five Team GB fighters have now progressed into the next round...
Lowestoft's Davison will take on number two seed Yuan Chang of China next.
Whittaker, a fighter tipped for Olympic glory by heavyweight champion Anthony Joshua, overcame Colombia's Jorge Luis Vivas by split decision in the men's light heavyweight category.
Vivas was a dangerous opponent for Whittaker, but the World Championship bronze medallist boxed with maturity and will now face Abdelrahman Oraby of Egypt in the last-16.
The final round saw McCormack clinch victory. He will now face the much fancied Andy Cruz of Cuba next - the number three seed and reigning world champion.
Team GB schedule (UK time)
9.15am: Men's flyweight
Galal Yafai (GB) vs Koryun Soghomonyan (ARM)
Tuesday, July 27
Pat McCormack (GB) vs Aliaksandr Radzionau (BY)
Caroline Dubois (GB) vs Donjeta Sadiku (Kosovo)
Cheavon Clarke (GB) vs Abner Teixeira (BR)
Wednesday, July 28
Lauren Price (GB) vs Myagmarjargal Munkhbat (Mongolia)
Thursday, July 29
Frazer Clarke (GB) vs Tsotne Rogava (UKR)