knock up
phrasal verb with knock verb uk/nɒk/ us/nɑːk/
(网球等运动中)赛前练习,赛前试打
Players knock up before beginning a game of tennis or similar sport by hitting the ball to each other.
The players have a couple of minutes to knock up before the match starts. 开赛前运动员有几分钟时间练球。