X550-T2 PCIe 2.0 x4

Hello, I'm looking around for an answer to this question and want to confirm something before making a good (or bad) decision...

The specs for the X550-T2 requires a PCIe 3.0 x4 slot; the X540-T2 required a PCIe 2.0 x8 slot I read online.

My motherboard currently only has one PCIe 2.0 x4 slot available.  Would the X550-T2 still work with one 10G connector using PCIe 2.0 and in the future I can upgrade to a PCIe 3.0 and then use both?  Or would the X550-T2 not function correctly under PCIe 2.0?

Thanks!