Guts moved up to Junior Welterweight (current Super Lightweight/Light Welterweight) in 1977, challenging Saensak Muangsurin, but was knocked out in the 6th round. Despite having moved up a weight class, Guts still had to shed 15 kg off his natural weight to make the weight-in.
In 1977, Guts stepped up to Junior Welterweight (now known as Super Lightweight/Light Welterweight), facing Saensak Muangsurin in a challenge that ended with a 6th-round knockout. Notably, Guts still had to reduce his weight by 15 kg from his natural level to meet the competition's weight-in standards.