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opposite player
opposite side; (person) directly opposite
「対面」 has another reading with different meanings.
麻雀で対面から上がりを宣言された。
In mahjong, the player across from me declared a win.
対面のプレイヤーの手が強そうだ。
The opposite player seems to have a strong hand.
麻雀で対面に座っている相手プレイヤーから牌を鳴いた。
I called a tile from the player across in mahjong.