Vernon Norwood 2nd, way back in 44.75. I though Makwala's 44.08 a few weeks back was maybe just a fluke, racing against Van Niekerk, but looks like he is in seriously good form.
He still has no chance against Van Niekerk, and virtually none against Kerley (unless Kerley is burnt out by finals at Worlds), but if he holds it together he could compete for bronze.
Sibanba and Nkobolo weren't very impressive, although I'm pretty sure Sibanda is coming off an injury.
LetsRun.com update: Videos of the races appear below.
43.92 400m https://www.youtube.com/watch?v=uMK89abEVQ0
19.77 200m https://www.youtube.com/watch?v=erss6lIDAyk
+0.0 wind in 200m