While Sumit stunned ninth seed Petru Ciobanu of Moldova 2-1, Vikash got the better of Poland's Dawid Michelus by a similar margin to be just two wins away from ensuring a medal.
Vikash opened the day for India and registered a hard-fought win over Michelus. Michelus won the opening round unanimously but the Indian came back strongly to clinch the second.
"It was a close bout no doubt but Vikash played aggressively and this win will definitely boost his morale. In the third round, Michelus was cautioned several times for his tactics but when he didn't relent then he was warned," national coach Gurbax Singh Sandhu told PTI.
Vikash will face fifth seed Miklos Varga of Hungary in the last-16 stage on Tuesday.
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Next up was Olympian Sumit and he continued his ascending march by stunning Ciobanu of Moldova.
Sumit will now face eighth seed Siarhei Novikau of Belarus in the pre-quarters tomorrow.