Top 25 Challenges must be made at individual tables. When you are ranked in the Top 25, you must have an open table and accept challenges there. If you challenge another player (regardless of your rank), but a better ranked player wins that challenge - you must then accept challenges at an open table (your own if you are Top 25). By challenging for an Up game you are showing that you are available to play. After that challenge is completed, you are then free to challenge for another Up game.