Sorry just wanted to add something to keep in mind
If your going up against someone you know you cannot beat, still go for it! No matter how long you wait, you will still be agaisnt that person, so get the loss out of the way and then reset the search. in 15 minutes you will have a new fighter. OR you could train, but that will take 10 hours, and by then you could have fought at least 39 other people. You can train and still fight the challenge