It's no secret that it is ridiculously hard to make the Kenyan (or Ethiopian) Olympic teams in the marathon this year, but is that the hardest qualification across all sports?
What about sports that have only one place per person? The GB men's track cycling comes to mind, with the reigning Olympic champion Chris Hoy (3 golds in 2008), and the 2012 reigning world champion Jason Kenny (1 gold and 1 silver in 2008) in contention for the single spot in the individual sprint.
What about other sports that are hugely popular in only a few countries? Korean Taekwondo team? Chinese pingpong or gymnasts? Brazilian Beach Volleyball?