This is off the top of my head, so I may have it wrong. But as I recall, the sporophyte generation of plants is diploid. They undergo meiosis to produce haploid spores. Those spores undergo mitosis, giving rise to the haploid gametophyte generation. It is the gametophyte generation that produces haploid gametes, which fuse to form a diploid zygote, which then grows into the sporophyte generation.
So...
Sporophyte (2n) --> spores (n, via meiosis) --> gametophytes 👎 --> gametes 👎 --> zygote (2n) --> sporophyte.
Hopefully that's right and made sense.