The following season Tkach won the 2016 Portugal Open against Ina Kaplan 7–4 winning her third Euro Tour event in a row. During the 2016 Kremlin World Cup, Tkach, along with Daria Sirotina was the only woman the round of the last 32 where she lost to Denis Grabe. She won her fifth Euro Tour medal at the 2017 Portugal Open losing 3–7 to Ouschan in the final. After finishing second in the one-year ranking of the Euro Tour after the Portugal Open, she qualified for the nine-ball Competition the World Games 2017. At the Games in Wrocław she lost in the quarter-finals against the subsequent gold medal winner Chen Siming. In the European Youth Championship 2017 she again won all three competitions for junior women. In the finals she defeated Daryna Sirantschuk (5–0, ten-ball), Weronika Karwik (5–0, eight-ball), Valery Trushevskaya (6–1, nine-ball). In November 2017, Tkach entered the 2017 WPA World Nine-ball Junior Championship where she reached the final before defeating Lee Woo-jin to become junior world champion. She was the fifth European and the second Russian, after Natalja Seroschtan (2013) to win the title.