Just finished trading on the Jovanovski - Krunic match, which lasted wooping 3 hours and 25 minutes (and that's on 36 degrees heat in Baku!). Decided to find out, which is the longest ever WTA match and came up with this...
"The longest women's match (by time) took place at a tournament in Richmond, Virginia, in 1984, when Vicki Nelson took 6 hours, 31 minutes to defeat Jean Hepner 6–4, 7–6(11). The match featured a 29-minute, 643-shot rally, the longest in professional tennis history. This match is also the longest professional match completed in a single day; the Mahut-Isner match was twice suspended by darkness, lasting three days." (Source: Wikipedia)