試合 and 大会: one match and a larger event
Read an individual match starting, a planned tournament entry, and handshakes after an event, keeping the scope and timing of 試合 and 大会 separate.
試合 (しあい): an individual match
「放課後に隣の学校と試合をした。」 (“We played a neighboring school after class.”) This reports a match against a neighboring school. It does not identify a winner or establish who won a larger tournament.
「雨がやみ、予定どおり試合が始まった。」 (“The rain stopped, and the game began as scheduled.”) The start belongs to this match. A match beginning as planned does not report its finish or the completion of an entire event.
大会 (たいかい): entering and finishing an event
「来月の水泳大会に参加します。」 (“I am participating in a swimming tournament next month.”) Keep next month's timing attached to the planned participation. Entering an upcoming swimming event is different from reporting that its matches have already been played.
「大会が終わると選手たちは互いに握手した。」 (“When the competition ended, the athletes shook hands.”) The handshakes follow the end of the event in this sentence. Do not combine it with the separate match-start example to invent a shared timetable.
Read the event name together with its timing
試合 focuses on an individual match, while 大会 names the broader competitive event. The examples do not establish a fixed number of matches or a universal format for every tournament.
Planned entry, a match starting, and an event ending are separate pieces of information. Check both what the noun names and what the sentence actually reports before turning participation into a result.
Does a plan to enter next month's swimming 大会 mean its 試合 have already started?
Show the answer and why
No. Planned participation does not establish that a match has begun. A report that one match started also does not report the end of the event or its winner.