Levski inflict first defeat on leaders Litex
Levski's 2-0 win at the Georgi Asparuhov kept alive their title hopes with four games remaining.
Champions Litex top the standings with 65 points followed by 26-times Bulgarian champions Levski on 60.
French-born Dembele netted his 23rd league goal in 20 games with a thunderous shot from the edge of the area after a precise pass from Dutchman Serginho Greene 15 minutes from time.
Levski, who finished the game with 10 men after defender Veselin Minev was sent off in the dying minutes, wrapped up victory when veteran Yovov scored from close range.
"They (Litex) still have a five-point lead but we know we could win the title if win all of our remaining matches," Levski coach Yasen Petrov told reporters.