Despite failing to win since the opening matchday, the hosts sit just one point shy of top spot in League C Group 3, while their visitors are also well-placed to finish first.
Match preview
At the end of a behind-closed-doors contest with Belarus on Saturday evening, Northern Ireland were left frustrated by failing to take their chances and claiming the win that would have put them top of the Group 3 table.
They ultimately had to settle for a goalless draw, despite testing the hosts' goalkeeper with several first-half attempts and seeing two strikes chalked off - first for offside, then for a foul.
As a result, Northern Ireland have won just two of their 19 Nations League games to date - failing to score in eight - and they occupy third place at the halfway stage of this year's edition.
However, Michael O'Neill's men can now return to Belfast, where they have won both of their last two home matches by a 2-0 scoreline; victory over Bulgaria would make it three wins in a row at Windsor Park for the first time since 2017.
Having begun their latest Nations League campaign by beating Luxembourg last month, thanks to early goals from Paddy McNair and Dan Ballard, Northern Ireland's second fixture brought a 1-0 loss in Bulgaria.
That leaves them winless in six meetings with Tuesday's visitors, posting a grim record of five defeats and one draw since coming out on top in May 1979.
Indeed, Bulgaria have kept a clean sheet on each of their last three trips to Belfast, and more recently they have been keeping the back door firmly shut against most opponents in 2024.
The Lions have fiercely defended their own area this year, conceding only two goals in seven matches, with none shipped throughout their Nations League campaign so far.
Bulgaria's last three games have seen just one goal scored in total - Kiril Despodov's strike in September's 1-0 victory over Northern Ireland - and they could now post four consecutive shut-outs for the first time since 2007.
Following Saturday's 0-0 home draw against last-placed Luxembourg, Ilian Iliev's side are locked together on five points with Belarus, and both sides are aiming to hold off each other and Northern Ireland to achieve automatic promotion by claiming top spot next month.
With that would also come a potential back-door route to the 2026 World Cup: a place in the playoffs, should they falter during qualification.
As Iliev is yet to lose as national team boss - though seven of his nine matches have ended in draws - Bulgaria may be confident of taking one step closer to that prize by winning at Windsor Park.
Northern Ireland Nations League form:
W
L
D
Northern Ireland form (all competitions):
W
L
W
W
L
D
Bulgaria Nations League form:
D
W
D
Bulgaria form (all competitions):
D
D
D
D
W
D
Team News
With goalkeepers Bailey Peacock-Farrell and Conor Hazard both missing due to injury, Michael O'Neill handed 19-year-old Pierce Charles his debut at the weekend, and the Sheffield Wednesday stopper could again feature behind elder brother Shea Charles, who is set to start in midfield.
ADO Den Haag striker Lee Bonis also got his first cap as a substitute, and he will compete with Callum Marshall and Jamie Reid for selection up front: the latter is back in action after a blood clot ruled him out of last month's matches.
Rising star Conor Bradley was given the captain's armband against Belarus, and no Northern Ireland player has won more duels (23), had more touches in the opposition's area (10), taken more shots (eight), or won more fouls (seven) in the Nations League this season.
While the hosts are without two goalkeepers, Leeds United midfielder Ilia Gruev is Bulgaria's most notable absentee, having recently suffered a serious knee injury.
Therefore, Valentin Antov, Georgi Kostadinov and Ivaylo Chochev are vying for two places in the visitors' engine room, at the heart of a 4-2-3-1 formation.
Up front, captain Kiril Despodov should support Aleksandar Kolev, though the latter has yet to get off the mark after nine caps without a goal. Despodov's winner in the reverse fixture was the 15th strike of his international career: the PAOK winger has scored both of Bulgaria's last two Nations League goals, and in four of their six wins to date.
Northern Ireland possible starting lineup:
P. Charles; Hume, McNair, Toal; Bradley, Saville, S. Charles, Price, Lewis; Marshall, Reid
Bulgaria possible starting lineup:
Mitov; Popov, Petkov, Atanasov, Nurnberger; Kostadinov, Chochev; Despodov, Krastev, Kirilov; Kolev
We say: Northern Ireland 1-1 Bulgaria
In a tightly contested group, with few goals and few wins, it could be another share of the spoils on Tuesday evening, as Bulgaria are particularly hard to beat.