Not in the Rules

A planet's strength was determined in the Arena where brute force emerged victorious. But the Earthman chose a forgotten weapon—strategy!
I got the bad news as soon as we landed on Mars. The minute I got off the spacer, the little yellow Martie was standing there with a yellow envelope. He said, Gladiator Jak Demsi?
I admitted it and he handed me the envelope. Made me feel kind of good, as though I was somebody important, which I'm not. I'd been taking plenty of guff on the trip. Not only from Suzi, but from Alger Wilde, who was also along. Yeah, between them they'd ridden me as well as the liner, all the way from Terra.
I handed the Martie a kopek and put the yellow envelope in my pocket, as though I was used to getting spacegrams.
I said to Suzi, Let's hit the chow line. I don't usually talk that fancy, but I was trying to impress her with my knowledge of antique phrases. Both Suzi and Alger Wilde are students of ancient times and love to lard their conversation with such stuff.
Suzi said, Sure, Jak. Come on Alger, which wasn't what I'd meant at all. And then she said, Aren't you going to open that spacegram, Jak? It might be important.
Probably is, I said carelessly. But it can wait, whatever it is.
And it did. I opened it after we'd ordered at the spaceport restaurant. I should have waited until after I'd eaten, but I couldn't know that until I read:
SPACER TRANSPORTING GLADIATOR EARTH-MARS FOR INTER-PLANETARY GAMES LOST. YOU HAVE BEEN APPOINTED EMERGENCY REPLACEMENT REPRESENTING EARTH. GOOD LUCK.
I gulped. If you don't know all about the Interplanetary Meet which is held every decade, then maybe you don't know why I gulped. If you do, you do. It's tough enough being a gladiator on Terra but at least you have a chance of coming out alive; you've even got a chance of winning. But at the Interplanetary Meet! Who ever heard of a Terran coming out in one piece? Not to speak of winning.
Sure, I'm a gladiator, but I've always been strictly a second rater; in fact, some of the sports writers call me a third rater. Anyway, I've always worked in the smaller meets where the gladiators, even when they lose, usually get off with their lives. In the small town stuff, they don't kill expensive gladiators, if they can help it.