Scotland moved top of Group 10 after a thrilling 2-2 draw away to Bulgaria but will wonder what might have been after conceding a 93rd-minute equaliser in Lovech.
Georgi Milanov gave the hosts a first-half lead only for two goals from Jordan Rhodes, his second in the 90th minute, to seemingly prise a victory for Scotland. There was a further twist, though, as Georgi Kostadinov restored parity in the dying seconds.
Billy Stark's team trailed the Netherlands by a point after five matches but knew a draw in Lovech would see them overtake them via their head-to-head record, while Bulgaria began proceedings a point adrift of their opponents.
Both sides failed to take early chances before Mihail Madanski's men broke through, Milanov exchanging passes with Aleksandar Tsvetkov before firing a powerful low shot past Mark Ridgers.
In the second half, Scotland came back strongly but had to wait until the 69th minute for the equaliser when Rhodes rose highest to head in after a quickly taken corner and cross from Gary Steven.
Another instinctive finish from Rhodes, his eighth in six group games, appeared to be decisive as the game headed into added time, only for Tsvetkov's last-gasp cross to reach substitute Kostadinov for a dramatic finale.