Alexander Tonev's hat-trick helped Bulgaria rout Malta 6-0 on Friday to move within one point of Group B leaders Italy in a match played behind closed doors because of racist incidents in a previous 2014 World Cup qualifier.
Despite freezing, windy conditions that made passing difficult, Bulgaria produced an inspired display of attacking football at the Vasil Levski national stadium to remain unbeaten.
Tonev, making a rare start in the absence of first-choice midfielder Stanislav Manolev, who suffered a thigh injury in training earlier this week, put the home side in front with a diagonal shot - his first international goal, after five minutes.
Tonev enjoyed a slice of luck for his second goal seven minutes before the break, his long-range effort appearing to pose little threat to Andrew Hogg but the Malta keeper allowed the ball to slip through his hands.
Captain Ivelin Popov made it 3-0 with an easy finish with Georgi Milanov, who became Bulgaria's youngest Footballer of the Year in December, providing a clever assist from the left wing two minutes after halftime.
Soon after, lively Emil Gargorov also managed to get his name on the scoresheet following a defensive mix-up and Tonev completed his hat-trick with another delightful shot from outside the penalty area.
Defender Ivan Ivanov added a sixth goal 12 minutes from time.
The game was played without spectators after FIFA punished Bulgaria following incidents during October's qualifier against Denmark in Sofia when a group of fans racially abused Denmark's Patrick Mtiliga.
Italy top the standings with 10 points from four matches, one ahead of Bulgaria, who have played one more game. Czech Republic, who face Denmark later on Friday, are third with five points from three matches.
Bulgaria visit Denmark on Tuesday while Italy travel to Malta and Czech Republic are away to Armenia.