Muscicapa flycatcher(s) Sumatra (1 Viewer)

I photographed this Muscicapa on 30 March 2018 in Pasaman Regency, West Sumatra Province and I could use some help with the ID. Muscicapa dauurica was quite common in the area, but this was the only bird I saw with any sign of streaking on the chest. I have very little experience with the genus, so any help would be appreciated. The likely taxa in the area are dauurica, williamsoni, sibirica, and rothschildi.
I photographed what I suspect is the same individual the following day, the photos of which I'll post in a reply to this post.

Thanks,

Oscar Johnson
Louisiana, USA

Photos of a bird the following day (31 March 2018), which I suspect are of the same individual as the post above.

Oscar Johnson

M. sibirica

Agree, Dark-sided Flycatcher.

Great, thank you

Oscar