In August 2020, Lillemets became Estonian champion in the decathlon at the
Estonian Athletics Championships having previously also won the
heptathlon at the
Estonian Indoor Athletics Championships in February 2020. He won the
pole vault at the 2021 Estonian Indoor Athletics Championships in February 2021. That year, he became the twelfth Estonian to eclipse the 6,000 point mark in the indoor heptathlon, and improved on his previous personal best result by almost 100 points to move to the seventh on the Estonian all-time list by scoring 6089 points in Tallinn to win the indoor heptathlon at the Indoor Estonian Combined Events Championships. In 2021, he finished fifth in the heptathlon at the
2021 European Athletics Indoor Championships in
Toruń, Poland, with 6055 points. He won the bronze medal in the Heptathlon at the
2023 European Athletics Indoor Championships in Istanbul, Turkey in March 2023 with 6079 points. In doing so, he became the fourth Estonian to reach the podium at the European Indoor Championships. He changed coach leaving
Erki Nool in early 2024, having worked with him since 2022, to join
Johannes Erm's large team, led by Holger Peel. In 2024, he was forced to withdraw from the decathlon at the
2024 European Athletics Championships in
Rome, Italy. He finished ninth in the heptathlon at the
2025 European Athletics Indoor Championships in
Apeldoorn, Netherlands, with 5922 points which included a personal best in the 1000m of 2.37.83. Shortly following that, he finished eighth at the
2025 World Athletics Indoor Championships in
Nanjing, China, with 5866 points. He placed third in the decathlon at the Wiesław Czapiewski Memorial in
Nakło nad Notecią, Poland, a World Athletics Combined Events Tour Gold event in July 2025. He placed eleventh overall overall in the season-long
World Athletics Combined Events Tour for 2025. == References ==