予選 and 決勝: competition stages and advancement
Distinguish qualifying rounds from finals and advancement from actually competing.
The qualifying stage
予選, read よせん, means a qualifying stage used to select participants for a later stage. 予選を通過しました。 means advancing through qualifying.
予選で敗れました。 means losing in qualifying. Do not move the loss to the final.
The final stage
決勝, read けっしょう, means the final that determines the winner. 決勝に進みました。 means reaching the final.
決勝は明日行われます。 says that the final takes place tomorrow. Do not translate it as an event already finished today.
Advancing and winning
決勝に進みましたが、まだ試合はしていません。 says that the person reached the final but has not played it yet.
予選を通過したからといって、優勝したわけではありません。 says that passing qualifying does not mean winning the competition. Intermediate stages depend on the particular event.
Does 決勝に進みました mean winning the competition?
Show the answer and why
No. It means reaching the final. Winning requires the final's result.