You only have to become stronger than your opponent

[Dehitay]

The more genius intellects amongst us may have already figured it out, but the sentence I'm trying to translate is "You only have to become stronger than your opponent". It's something to be said for something like training for a martial arts match, implying that you don't have to become the strongest person in the world to win. My best attempt is currently
敵より強くなるだけしなくてはいけません
While that's probly going to be understood, I have 2 concerns with it. First, I don't think 敵 is the right word for this context. It seems a bit stronger than it needs to be, but I could be wrong. Also, it seems like　なるだけしなくてはいけません might be bad grammar. ならなくてはいけないだけ was another thought, but for some reason, I'm not sure if that fits the context. Or maybe the whole sentences needs a 勝利のために preceding it to add context.

[Hyperworm]

（世界一最強の人になる必要はない。）相手より強くなれ（れ）ばそれでいい。
I keep thinking you might be able to do something with さえ (相手より強くさえなれば...??) but it's not quite sounding natural for me...

(I don't think you need なくてはいけない here. The core structure of the sentence isn't "You must become stronger than ...", it's "It's enough just to become stronger than ...".)

[spin13]

I keep thinking you might be able to do something with さえ (相手より強くさえなれば...??) but it's not quite sounding natural for me...

I don't think it works here either. なればいい or なれば十分だ seem good enough.

I've never seen an adjective in the ～くさえ～ば form without using ある (あれば). Can anybody confirm whether it is permissible to use other verbs?

[Reft]

I keep thinking you might be able to do something with さえ (相手より強くさえなれば...??) but it's not quite sounding natural for me...

I don't think it works here either. なればいい or なれば十分だ seem good enough.

I've never seen an adjective in the ～くさえ～ば form without using ある (あれば). Can anybody confirm whether it is permissible to use other verbs?

You often hear ～さえなければ being used e.g. "資料さえ忘れなければプレゼンはうまくいくだろう”

However 相手より強くさえなれば Would roughly translate to "As long as your not stronger than your opponent".　And I agree, it doesn't really seem to scan either way.

Context is clearly important here, I don't really understand fully the mood in which it would be said I have no martial arts experience, or if such a saying would even make sense in Japanese, so I'm just conjecturing. But something like Hyperworm said ”相手より強くなればそれでいい”　or ”相手の力を超えるだけだ”. It may be one of these situations in which it just won't work in Japanese however you phrase it as so frequently happens. I've had no end of people ask how to say "よろしくおねがいします”　or いただきます　in English and never really been able to offer them a decent explanation.

[Dehitay]

Wow, who would have thought that the time honored tradition of trying to translate English words directly into Japanese would fail yet again for the 1000th time? Thanks for the help. I've been absent from my studies for too long, and now it's near impossible for me to get into a Japanese mindset for this kind of thinking.

[Stefan]

これがいかがであります？　
ひとたびMANGAJINで読みました。

相手を知れば、百戦あやうかならず
opponent (obj) if know, 100 battles(usually just translated as many battles) safe
know your opponent and be safe though many battles. Hope I helped even a little.