on serve

Prepositional phrase

(tennis) With each player or pairing having won the same number of games as they have served.

Japanese Meaning

（テニスにおいて）各プレイヤーまたはペアが、サーブした回数と同じ数だけゲームに勝利している状態を示す。

The match remained tense and on serve until the final game, when a single break decided the winner.

試合は最終ゲームまで両者ともサーブで獲得したゲーム数が同じままで緊迫していたが、最後のゲームでわずか一度のブレークが勝者を決めた。

Sense（1）

(tennis) With each player or pairing having won the same number of games as they have served.