While Freiburg have won three of their last four league games, Leverkusen have lost three of their previous four, leaving them 13 points shy of Christian Streich's side.
Match preview
With the top six teams in the Bundesliga table separated by only five points, fourth-placed Freiburg must be viewed as genuine title contenders as we approach the final third of the campaign.
Not only have Streich's men lost just four of their 21 league matches this season, but they have also picked up 12 wins along the way - the same number of victories as table-topping Bayern Munich.
After kicking off their Bundesliga campaign with a run of one defeat in nine outings, Freiburg secured four wins in five games before the winter break to cement second place in the standings ahead of the World Cup.
Although Breisgau-Brasilianer have struggled for consistency since the restart - recording three wins, one draw and two losses in the league - they remain firmly in contention for the title.
Freiburg suffered a 5-1 thrashing at the hands of Borussia Dortmund earlier this month but bounced straight back with victories over Stuttgart and VfL Bochum, staying within touching distance of the leading pack.
Bayer Leverkusen head into Sunday's clash having booked their place in the Europa League round of 16, with Xabi Alonso's side dispatching French club Monaco on penalties.
Monaco won the first leg 3-2 at BayArena, but Leverkusen produced a 3-2 win of their own on Thursday, with goals from Florian Wirtz, Exequiel Palacios and Amine Adli forcing extra time.
Although Leverkusen eventually prevailed on penalties, they cannot afford to get carried away with their success on the European stage, as a run of three losses in four league matches has left them 10th in the Bundesliga standings.
After failing to score in defeats to Borussia Dortmund and Augsburg, Die Werkself claimed a 3-1 win at Hoffenheim before suffering a 3-2 home defeat against Mainz 05 last weekend.
It is also worth noting that Leverkusen have lost four of their previous seven away league outings, conceding 12 goals across those defeats, with a solitary clean sheet coming in their 10 Bundesliga away trips this term.
Freiburg Bundesliga form:
L
D
W
L
W
W
Freiburg form (all competitions):
D
W
L
W
W
W
Bayer Leverkusen Bundesliga form:
W
W
L
L
W
L
Bayer Leverkusen form (all competitions):
L
L
W
L
L
W
Team News
Freiburg will be without the suspended Christian Gunter on Sunday, as the club captain picked up his fifth yellow card of the campaign in last weekend's 2-0 at Bochum.
Gunter has started all 21 of Freiburg's Bundesliga games this season, with Kiliann Sildillia expected to return to the side in the left-back's absence.
The hosts will also be without Daniel-Kofi Kyereh for the remainder of the campaign after the midfielder sustained an ACL injury earlier this month.
Bayer Leverkusen have three suspensions to navigate this weekend, as Amine Adli was sent off in last weekend's defeat to Mainz, while Piero Hincapie and Jonathan Tah received their fifth yellow cards of the season.
Mitchel Bakker is likely to replace Tah in Leverkusen's backline, with Florian Wirtz expected to come in for the absent Adli.
On top of that, Die Werkself still have Dalet Sinkgraven, Andrey Lunev and Charles Aranguiz sidelined due to injury.
Freiburg possible starting lineup:
Flekken; Kubler, Ginter, Lienhart, Sildillia; Eggestein, Hofler; Doan, Holer, Grifo; Gregoritsch
Bayer Leverkusen possible starting lineup:
Hradecky; Frimpong, Tapsoba, Bakker, Kossounou; Demirbay, Andrich, Amiri; Wirtz, Azmoun, Hudson-Odoi
Fiorentina 
Udinese 
Benfica 
Estoril 
Inter 
Como 
Manchester City 
Everton 
Chelsea 
Fulham 
Nottingham Forest 
Tottenham 
Celtic 
Motherwell 
Wolverhampton 
Manchester Utd 
ST Mirren 
Rangers 
Sampdoria 
Carrarese 
Liverpool 
Leicester 
Arsenal 
Ipswich 
Cagliari 
Lazio 
Atalanta 
FC Porto 
Boavista 
Torino 
Napoli 
Venezia 
ST Johnstone 
Juventus 
West Ham 
Pisa 
AC Milan 
Roma 
Sporting CP 
Newcastle 
Brentford