knock-up

knock-up
ˈknock-up noun [countable] British English
the time before a tennis match officially starts when the players hit the ball to each other for practice ⇨ warm-up

knock-upBrE /ˈnɒk ʌp/ 🔊NAmE /ˈnɑːk ʌp/ 🔊 noun (BrE) a short practice before a game, especially of tennis （尤指网球的）赛前练习