While a 1-1 draw with 10-man Lithuania on Saturday was disappointing for Mladen Krstajic, the Serbs retained top spot despite not playing over the weekend.
Match preview
Even though Justas Lasickas was dismissed for a professional foul after 17 minutes, Bulgaria could only find an equaliser against Lithuania.
Marin Petkov levelled for the away side just before the half-hour mark after Edvinas Girdvainis's 15th-minute opener put the hosts 1-0 up.
Quality chances were limited for Krstajic's men, who had to shoot from far out when they could not find a way past Lithuania's deep defence.
The result leaves them with one point from a possible nine, bottom of Group I, and undoubtedly facing an uphill task of playing at next year's European Championship.
With goalscoring a bugbear — Bulgaria have scored once in three matches in qualifying — it remains to be seen how they get past a Serbia side without a goal conceded in their opening two games.
As for the visiting side, they could have been joint-top of the group had Hungary or Montenegro won on Saturday, but a 1-1 draw between the pair leaves Dragan Stojkovic's men two points clear, having played a game fewer than the Montenegrins.
A pair of 2-0 victories to start qualifying in March has put the Eagles in the driving seat ahead of their third game, and maximum points against the section's bottom side seems likely.
Despite his mixed campaign with Juventus, Dusan Vlahovic has netted three of the away side's four goals, with Dusan Tadic scoring the other, and the centre-forward could play a pivotal role in Tuesday's result.
Serbia have not made it to four consecutive European Championship finals; thus, their relatively straightforward group and bright start in qualifying have placed them in a favourable position.
Beaten by Scotland in the Playoff final preceding Euro 2020, Stojkovic's men could benefit from the top two teams advancing to next year's competition.
Bulgaria Euro Champ Qualifying form:
L
L
D
Bulgaria form (all competitions):
W
W
D
L
L
D
Serbia Euro Champ Qualifying form:
W
W
Serbia form (all competitions):
D
L
W
W
W
W
Team News
Krstajic is not expected to alter his approach from the 5-4-1 utilised in Lithuania, even if the manager may consider personnel tweaks.
There might be some temptation to start Georgi Rusev for the first time in qualifying after his commendable cameo on Saturday, although dropping Kiril Despodov will not be an easy call.
Daniel Naumov lost his spot between the sticks to Ivan Dyulgerov, and it remains to be seen if Bulgaria retains the custodian on Tuesday.
Stojkovic is anticipated to continue with the 3-4-2-1 hitherto utilised in qualifying, although the manager tends to make changes due to the options at his disposal.
Sergej Milinkovic-Savic is expected to start in central midfield or further forward as one of the number 10s along with Tadic.
That call would affect Vlahovic's chances of starting, especially as Stojkovic favours Aleksandar Mitrovic as his central striker.
Bulgaria possible starting lineup:
Dyulgerov; Galachev, Petkov, Antov, Gruev, Petkov; Despodov, Chochev, Shopov, Delev; Minchev
Serbia possible starting lineup:
Milinkovic-Savic; Milenkovic, Gudelj, Pavlovic; Zivkovic, Grujic, Milenkovic-Savic, Mladenovic; Tadic, Vlahovic; Mitrovic