can't possibly win, have no chance of winning
絶対、勝てっこないって。
There's absolutely no way we can win.
どうせ勝てっこないよ。
There's no way we'll win anyway.
やらなきゃ勝てっこないよ。
If you don't do it, there's no way you'll win.
勝てっこないさ。
There’s no way we can win.