Bǐsài qián tā bǎ duìshǒu de lùxiàng kàn le hǎojǐ biàn, yīnwei zhījǐ-zhībǐ, cái néng bǎizhàn-búdài.
Before the match he watched his opponent's videos several times over, because knowing yourself and your enemy keeps you safe in every battle.
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mistakes
殆 means 'danger', so this is 'never in danger', not 'win every battle'. The popular version 知己知彼，百战百胜 changes the meaning: the 孙子兵法 says winning every battle is not the highest skill, and that winning without a fight is better.
