[1] Vasilev's twin brother Viktor is playing for CSKA 1948 III.
Vasilev started his career in Tigers local academy, before moving to Levski Sofia in 2013.
[3] Simeon completed his professional debut on 22 September 2023, in a league match against Cherno More.
[4] On 1 August 2024, he sustained a serious injury during the second leg against Montenegrin team Budućnost Podgorica in a UEFA Conference League qualifying match, which subsequently necessitated an operation in Barcelona.
This biographical article related to association football in Bulgaria, about a defender, is a stub.