Monko/Tkachenko won a pair of medals on the Junior Grand Prix series and qualified for the JGP Final where they took gold.

They finished fourth at the 2008 World Junior Championships after Monko fell on twizzles in both the original and free dance.

Monko/Tkachenko received two senior Grand Prix assignments, 2008 Skate America and 2008 Trophée Eric Bompard, and prepared new programs.

After a tryout, they both felt it would be a good partnership, despite her needing time to adapt to his different technique and some disapproval from the Russian skating federation.

[10] They placed fifth at their first Grand Prix event of the season, the 2010 Skate America, and then won silver at the 2010 Trophée Eric Bompard.

On their free dance, which was choreographed by Sergei Petukhov, Riazanova said, "A young woman remembers her beloved, who is no longer alive.

[19] At the suggestion of Tatiana Tarasova, they decided to scrap a new free dance to Pink Floyd's Hey You and made a new one to a waltz from the Godfather films.

[23] Tobias/Tkachenko began the season on the Challenger Series (CS), winning silver medals at the Finlandia Trophy and Mordovian Ornament.

After placing 6th at the 2016 Skate America and 5th at the 2016 Trophée de France, they won silver behind Elena Ilinykh / Ruslan Zhiganshin at the 2016 CS Tallinn Trophy.

Due to their result, Israel qualified a spot in the ice dancing event at the 2018 Winter Olympics in Pyeongchang, South Korea.

[4] On 12 April 2017, Tobias/Tkachenko announced a coaching change, having decided to join Marina Zoueva, Oleg Epstein, Massimo Scali, and Johnny Johns at the Arctic Edge in Canton, Michigan.

Due to Tkachenko's unsuccessful application for Israeli citizenship, they were not included in Israel's team to the 2018 Winter Olympics.

[6] In January 2019, Tkachenko moved to Estero, Florida, to coach at the Hertz Arena's International Skating Academy.