Learn Russian: Прежде чем ударить по шару, игрок подошёл к столу. - Before hitting the ball, the player approached the table.

When the subject of the main clause (игрок) is the exact same as the subject of the subordinate clause, прежде чем is followed by an infinitive. If the subjects were different (for example, 'before I hit the ball, the player approached'), you would need to use a past tense verb in the subordinate clause.

Why is it ударить по шару instead of just using the direct object ударить шар?

In Russian, verbs describing a physical strike often take the preposition по followed by the dative case. While ударить шар (accusative) is grammatically possible, ударить по шару emphasizes striking the surface of the object, which is the most natural way to describe hitting a ball in games like billiards or golf.

Could I use the imperfective verb бить instead of the perfective ударить here?

Using the perfective ударить shows that the player is preparing for a single, completed strike. If you used the imperfective бить, it would imply 'before starting to hit' or 'before repeatedly hitting' the ball, which does not fit the context of taking a single shot in a game.

What does the prefix in подошёл mean, and why must it be followed by к?