Your first attempt Error014 really confused me, I don't think it needs to be complex but you gave me the basic idea of calculating where the ball and player will be.

If I know t I can calculate using formulas how far each character will be to the ball. So yes I calculate 500 times, t = 1, t = 2, find the distance from the player to the ball from the player's and ball's position at t. When I've found the shortest distance I store the time value. I then find the player which has the smallest t value and make that player run towards where the ball will be

Nope there was no solution, even the way I have implemented fails at certain times and it's not really clean to calculate 500 times for each character each frame, I could do it less if I wanted. But one set of code which simply calculates what t is at, as you've all so graciously been doing, would be the best solution.