\\8abc<(a+b)(b+c)(c+a)\\$Since, $x+y-z>0, y+z-x>0 $ and $ z+x-y>0\\$We can let $a=x+y-z, b=y+z-x $ and $c=z+x-y\\8(x+y-z)(y+z-x)(z+x-y)\\<((x+y-z)+(y+z-x))((y+z-x)+(z+x-y))((z+x-y)+(x+y-z))\\=2y\times 2x \times 2z\\=8xyz\\$Hence, $(x+y-z)(y+z-x)(z+x-y)< xyz