Or, better still...The player who kicked the ball had clearly planned the move with the forward to whom he kicked it.
EXPLANATION Notice that in the example above, the noun player has been replaced by a pronoun. That pronoun needs to be who because it is acting as the subject of the clause who kicked the ball (i.e. the player kicked the ball). Whenever the relative pronoun is to be the subject of the clause in which it stands, we use who. Most people would automatically use ‘who’ in that situation, so that is not likely to be a problem.
On the other hand, if the relative pronoun is to be the object of a verb or preposition, theoretically we should use whom. In the corrected typical error above, the best phrasing would be the forward to whom he kicked it. Here, whom is the object of the preposition to - which is why it is technically more correct to say to whom he kicked it than to use the everyday phrasing with the preposition at the end of the sentence. Indeed, if we use the correct phrasing (to whom), it is easy to see that the object of to should be whom.
Here are some examples of how who and whom should be used. The relevant verbs or prepositions have been italicised to help you to understand.
- The man who is fishing from the bridge has caught three whiting.
- The film star about whom I told you is starring in this film.
- The person whom I would choose as captain is Laura Peters.
- Have you ever seen anyone who can eat so much food?
- To whom were you speaking?
- Is he the sort of person with whom you could work happily?
- Who is likely to win the election?
- She is someone for whom we have the greatest respect.
- She is the best boss for whom I have ever worked.
- Who has been chosen to carry the flag?
Incidentally, the same rules apply to whoever and whomever. Thus we would say
but
If you find the difference between who and whom confusing, it is better just to use who all the time.