1. He used to be a member of Neposedi (Непоседы), the band in which the two singers from t.A.T.u met.
Yulia Volkova and Lena Katina, who later formed, t.A.T.u. were both in the children's band Nepodesi with Sergey. The band still exists in Russia, but its members have gone through many iterations — kind of like the Sugababes.
2. His niece Alina is now part of the group.
3. He later joined forces with former Nepodesi bandmate Vlad Topalov to form a new duo called Smash!! (СМЭШ!!).
4. He runs a confectionery shop for dogs called Pudel Shtrudel.
5. He trained to be a professional actor at MKHAT and MAAT theatre schools.
6. He came second on the Russian version of Dancing on Ice in 2006.
7. And first in Circus with the Stars in 2007.
8. He had a very high profile relationship with Russian TV presenter Lera Kudryavtseva.
9. In 2008, he got to the Russian national selections for Eurovision.
10. He has been a judge on the Ukrainian version of The Voice.
11. He has spoken out about LGBT rights in the past.
12. His 2016 Eurovision entry "You Are The Only One" is written by Dimitris Kontopoulos, who has written five previous Eurovision entires, and Philipp Kirkorov who has written two and performed in the contest in 1995.
13. Sergey does voiceover work in Russia: He is the voice of Prince Arthur from Shrek the Third.
14. He's also the voice of Humphrey from Alpha and Omega.
15. And Troy Bolton from High School Musical.
16. His performance is kind of like Måns Zelmerlöw's winning peformance last year: It's suuuuuper hi-tech.
