Definition
In tennis or similar sports, players warm up by rallying the ball to each other before the game starts.
（網球等運動）賽前練習
Before the match, players usually knock up to prepare themselves for the game.
比賽前，球員通常會先進行賽前試打，為比賽做好準備。
The coach asked the players to knock up thoroughly before the game to ensure they are ready.
教練要求球員在比賽前徹底進行賽前試打，確保他們已準備好。
We always arrange to knock up together before the season starts to improve our performance.
我們總是在賽季開始前安排一起賽前試打，以提高我們的表現。