The pair kick off their third qualifying round tie with the winners after next week's second leg advancing to the playoff round; the losers will slip into the Europa League.
Match preview
Though their flawless start to Champions League qualifying came to an end last week, at the hands of Shamrock Rovers, a 4-2 aggregate victory in the second round saw Ludogorets through to the penultimate stage of the process.
The Bulgarian First League champions comfortably overcame Montenegro's Niksic in the first round - winning the first leg 2-0 at home before adding a 1-0 victory in the reverse fixture - and were three goals to the good before travelling to Dublin on Wednesday.
Losing to Shamrock has been the Eagles' only reverse since returning to competitive action at the start of last month, just weeks after sealing an 11th straight domestic title.
Having taken part in the Europa League during both of the last two seasons, after falling short in the qualifiers for Europe's top tournament, Ludogorets are targeting a first return to the promised land since 2016 - one of two previous appearances in the Champions League group stage.
Ante Simundza's side have been in league action already this summer, and a total of 10 points from their opening four First League fixtures puts them top of the table on goal difference - aided by Friday's 5-0 win over Spartak Varna.
Dinamo Zagreb, meanwhile, have trodden a similar path to their latest Champions League opponents during July, posting three wins from three to take maximum points in the 1. HNL.
Friday night's 4-1 victory against Istra was Dinamo's fourth from five games since lifting the Croatian Super Cup on penalties last month, and their only draw came in continental competition, against Macedonia's Shkupi.
Following a 2-2 result in the home leg of their second round tie - the stage at which they entered the competition - the Blues then edged through by virtue of a 1-0 win in Skopje.
Arijan Ademi scored the decisive goal early in the second half, having found the net back in Zagreb too, as the Croatian champions took the first step on another European campaign in an era of relative success for the club - they reached the Europa League quarter-finals in 2021 and the last 16 two years previously.
Five league titles in a row means Dinamo's domestic supremacy is unquestioned, but they have failed to reach the Champions League group phase since 2019 - like Ludogorets, falling at the final hurdle last year - so the stakes will be high when they travel to Razgrad.
Ludogorets Razgrad Champions League form:
Ludogorets Razgrad form (all competitions):
Dinamo Zagreb Champions League form:
Dinamo Zagreb form (all competitions):
Team News
Ludogorets coach Ante Simundza has an eclectic squad from which to choose, and alongside Bulgaria internationals Kiril Despodov and captain Anton Nedyalkov, several players drawn from across Africa and South America will feature on Wednesday.
A naturalised Bulgarian since 2018, Brazil-born Cicinho should again feature at right-back for the hosts, in a probable 4-3-3 formation.
Cypriot striker Pieros Sotiriou starts up front, but Manuel Cafumana is suspended following his red card at Tallaght Stadium last week.
Meanwhile, Dinamo have strengthened their options over the summer, signing Swiss forward Josip Drmic and ex-Atalanta defender Bosko Sutalo.
The former must compete with Bruno Petkovic and Mislav Orsic for a start up front, having scored three league goals in as many matches this season; the latter will hope to usurp either Rasmus Lauritsen or Dino Peric in the visitors' back four.
Fellow defender Kevin Theophile-Catherine remains a doubt, though, due to injury - Iran international Sadegh Moharrami should therefore start at right-back.
Ludogorets Razgrad possible starting lineup:
Padt; Cicinho, Verdon, Plastun, Nedyalkov; Santana, Iordanov, Cauly; Despodov, Sotiriou, Rick
Dinamo Zagreb possible starting lineup:
Livakovic; Moharrami, Lauritsen, Peric, Ljubicic; Spikic, Misic, Ademi, Ivanusec; Orsic, Petkovic
We say: Ludogorets Razgrad 2-2 Dinamo Zagreb
Both sides certainly know the way to goal and are comfortable taking the initiative, so this looks to be a well-balanced tie on paper. Therefore, the scores could be level ahead of next week's return leg.