Similar to the "simulate a fair coin from a weighted coin" algorithm:
> The number of Ping-Pong balls was chosen because there are exactly 1,001 ways that four numbers can be drawn from a set of 14. Each of those combinations is assigned to a team. [...] The 1,001st and final combination — 11, 12, 13, 14 — is unassigned; if it is drawn, the balls will be put back and drawn again.