I recently started taking an interest in General Relativity, however I am well aware that I simply have no knowledge of the mathematics behind it, especially Riemannian geometry.
That being said, I wish to learn as much as possible about Riemannian geometry, but am a year or so away from even being an undergraduate therefore my knowledge is severely lacking.
I have had a look at some related questions asking for book recommendations and have even (tried to) read some of them, but have found that they expect a far stronger mathematical background than my own, hence my question:
Assuming an undergraduate student in their first or second year at university, what topics would they need a thorough understanding of before they read any introductions to Riemannian geometry?