godan verb (-su), intransitive verb
have more wins than losses; be ahead in wins
Describes a cumulative record over a series of matches, such as a tournament or season. Often used with a margin, e.g. 2つ勝ち越す (to lead by two wins).
Antonyms: 負け越す
今場所は10勝5敗で勝ち越した。
He finished the tournament with a winning record of 10 wins and 5 losses.
The team currently has one more win than loss.
godan verb (-su), intransitive verb
take the lead (in points, goals, etc. during a match)
Refers to being ahead in score within a single game or match, not the overall win-loss record. Common in live sports commentary.
3回裏、タイムリーで1点勝ち越した。
In the bottom of the third inning, they took a one-run lead with a timely hit.
後半に入ってすぐに勝ち越しゴールを決めた。
They scored the go-ahead goal right after the start of the second half.