The home side beat Sutjeska Niksic in the last round to advance to this stage, while League of Ireland Premier Division side Shamrock comfortably overcame Maltese outfit Hibernians.
Match preview
Ludogorets comfortably dispatched Niksic in the first qualifying round of this season's Champions League, winning the first leg 2-0 on home soil before recording a 1-0 victory in the second leg one week later.
The Eagles secured their spot in the first qualifying round of the Champions League courtesy of winning Bulgaria's top flight for the 11th time last season, and they will be the favourites to advance from this two-legged affair with their League of Ireland Premier Division opponents.
Ludogorets operated in the group stage of the 2014-15 Champions League, taking on Real Madrid, Basel and Liverpool, while they also made the groups of the 2016-17 tournament.
Ante Simundza's side lost to Malmo in the playoff round of last season's Champions League before competing in the group stage of the Europa League, finishing fourth in Group F.
Ludogorets started their league season towards the start of the July, and they have beaten Septemvri Sofia and Lokomotiv Plovdiv in their opening two games to sit at the top of the division with six points.
Shamrock, meanwhile, beat Hibernians 3-0 in the first leg of their first qualifying contest on July 5 before playing out a goalless draw with the Maltese side on July 12 to advance to the next round.
Rovers are already 23 matches into their league season, collecting 51 points from their 23 matches to sit at the top of the division, nine points clear of second-placed Dundalk.
Stephen Bradley's side are next in League of Ireland Premier Division action on July 22 against Drogheda United, with their two legs of this European contest taking place either side of the league encounter.
Shamrock, who have won their domestic title on 19 occasions, lost to Flora in the playoff round for last season's Europa Conference League after overcoming Teuta in the third qualifying round.
The Hoops played in the group stage of the Europa League back in 2011-12, finishing fourth in a section which included English giants Tottenham Hotspur.
Ludogorets Razgrad Champions League form:
Ludogorets Razgrad form (all competitions):
Shamrock Rovers Champions League form:
Shamrock Rovers form (all competitions):
Team News
Ludogorets were in league action against Lokomotiv Plovdiv on Friday, and head coach Simundza rung the changes from the second leg of their first qualifying round contest in the Champions League.
Cauly, Pieros Sotiriou and Spas Delev were all rested from the start before featuring late on last time out, and the trio will be back in the starting XI for this contest.
There will also be returns in the full-back areas for Anton Nedyalkov and Zan Karnicnik, with Simundza set to name his strongest available side for the clash with the Irish outfit.
Shamrock could be missing Neil Farrugia and Jack Byrne due to muscular problems, but the away side have not reported any fresh injury concerns ahead of this contest.
Ronan Finn, Dylan Watts and Rory Gaffney were all on the scoresheet against Hibernians in the first leg of their first qualifying round contest, and the trio are again expected to start here.
There should also be a spot in the final third of the field for experienced centre-forward Aaron Greene.
Ludogorets Razgrad possible starting lineup:
Sluga; Karnicnik, Verdon, Plastun, Nedyalkov; Santana, Show; Delev, Cauly, Despodov; Sotriou
Shamrock Rovers possible starting lineup:
Mannus; Lopes, Grace, Hoare; Finn, McCann, O'Neill, Lyons; Watts; Greene, Gaffney
We say: Ludogorets Razgrad 2-1 Shamrock Rovers
Shamrock must stay in the contest on Tuesday if they are to stand a chance of progressing to the next round of the competition. Ludogorets will fancy their chances of winning the first leg, but we are expecting it to be a close affair in Razgrad.