Thinking it in the same time that I write it, so it may not be hugely coherent.
1) A crushing French victory in the Sino-French war, it could lead to not only a lesser Chinese presence in southern seas (Pesacores Island being probably swalloed up by France, for exemple)
2) An harsher Russian pressure (no Treaty of 1881, or at least, one more favourable to Russia) on Turkestan and early on Manchuria, up to a Russian protectorate on Korea.
I'm not sure on how much both of these are plausible and if it could really have as much consequences, but making European powers the monopolizers of two regions that Japan had interest to (Korean peninsula and South China Sea) could lead to a rough alignment.