also: にっぽんせん
noun
Japan match; game involving Japan
Refers to a sports match or game in which the Japanese national team or a Japanese representative is playing. Commonly used in contexts like soccer, baseball, rugby, etc.
今夜の日本戦は絶対に見逃せない。
I definitely can't miss tonight's Japan match.
ワールドカップの日本戦のチケットが当たった。
I won tickets to the World Cup Japan game.
国際試合 is a more general term for any international match, while 日本戦 specifically indicates a match involving Japan.
Compound of 日本 (Japan) and 戦 (match, game, war). The suffix 戦 is commonly attached to country names to denote a match against or involving that country.