Hot take in the middle of a match, but based on the last 6 months: Johanna will not finish 2018 as GB #1. Not due to injury, or some other player performing amazingly, just due to loss of form.
I don't say this lightly; you can track my ardent support of Jo back years on this forum, long before her big successes.
__________________
Data I post, opinions I offer, 'facts' I assert, are almost certainly all stupidly wrong.
Jo saved 3 match points but had to play very well to do it, with Pera hitting winners off some of Jo's serves. So far Jo has hit 13 winners to Pera's 21.
Jo 4-5*