Coached by Ludmila Velikova, Nikolai Velikov and Vasilii Velikov, Akhanteva/Kolesov started their season in August on the 2018 JGP series. Ranked second in the short and third in the free, they won the bronze medal in Bratislava, Slovakia, contributing to a Russian sweep of the pairs' podium. Akhanteva/Kolesov were more than 11 points behind the champions, their training partners Anastasia Mishina / Aleksandr Galiamov, but lost to the silver medalists, Apollinariia Panfilova / Dmitry Rylov, by a margin of only 0.13 points. In September, they outscored their teammates and training partners, Polina Kostiukovich / Dmitrii Ialin, by about four points for gold at the JGP in Ostrava, Czech Republic, where they were second in the short program and first in the free skate. With these results they qualified to the 2018–2019 Junior Grand Prix Final, where they placed fourth overall. Akhanteva/Kolesov went on to compete at 2019 Russian Nationals, their first ever senior competition, and finished tenth there. Unfortunately they had to withdraw from the junior event after Kseniia seriously injured her leg.
2019–2020 season
Akhanteva/Kolesov started their season with a silver medal at the 2019 Junior Grand Prix competition in Lake Placid, United States. Ranked second in the short and second in the free, they finished 15 points behind the gold medalists Apollinariia Panfilova / Dmitry Rylov, in part due to costly jumping errors in both programs. Two weeks later Akhanteva/Kolesov took the gold at JGP Chelyabinsk, Russia. Ranked first in the short program and first in the free skate, they finished eight points ahead of silver medalists Iuliia Artemeva / Mikhail Nazarychev, and led a Russian sweep of the pairs' podium at their home JGP. At this event Akhanteva/Kolesov became the first junior pairs team to break 40 TES in the short program. Their results qualified them to the 2019–20 Junior Grand Prix Final in Torino, where they won the bronze medal. Competing at the 2020 Russian Championships at the senior level, they placed tenth. Having then won the silver medal at the junior championships, they were named to Russia's team for the 2020 World Junior Championships. Second in the short program with a clean skate, Kolesov nevertheless said he felt it was not their best performance and stated their goal was to achieve a season's best result in the free. In that segment, Akhanteva fell on both side-by-side jump attempts and put a foot and hand down on one of their two throw jumps, but they nevertheless remained in second place and won the silver medal overall due to errors by third- and fourth-place finishers Artemeva/Nazarychev and Hocke/Kunkel. Kolesov acknowledged "the performance was bad today. I don't know the reason, but the result is good, because the short program was good."
