noun
play-off; tiebreaker
Used in sports and competitions when scores are tied and an extra round or match decides the winner.
試合は同点決勝にもつれ込んだ。
The game went into a play-off.
延長戦 is extra time added to a match, while 同点決勝 is a separate tie-breaking round or match after a tie.
Compound of 同点 (tie score) and 決勝 (deciding match).