keep one's eye on the ball
To watch the ball at all times in a sport, usually in order to hit it or get it; not stop watching the ball.
Keep your eye on the baseball or you won't be able to hit it.
To be watchful and ready; be wide-awake and ready to win or succeed; be smart.
Быть на чеку; контролировать ситуацию; быть расторопным.
Tom is just starting on the job but if he keeps his eye on the ball, he will be promoted.
He was told that during the meeting he must keep his eye on the ball and concentrate on the matter at hand.
Ему было приказано во время встречи быть полностью во внимании и сконцентрироваться на предмете.
We tried to keep our eye on the ball during the meeting.
Мы старались быть на чеку во время встречи.