Seoul boss Choi Yong-Soo believes that the return of Adilson can help power his side into the semi-final of the AFC Champions League.
Seoul made the ideal start to the first leg against Al Ahli, going ahead after 10 minutes through forward Dejan Damjanovic.
However, Sultan Al Sawadi's equaliser ensured that the tie remains very much in the balance ahead of Wednesday's second leg.
With the Brazilian defender having served the suspension that kept him out of the tie in Saudi Arabia, Choi is hopeful that the 37-year-old can swing the balance in his side's favour.
"Adilson is a reliable player who has played for the club for a long period of time," Choi told the Asian Football Confederation website. "He is the core of our team and his return will definitely help our side."
The South Korean champions go into the clash in fine form, having avoided defeat in their last seven league games, with Choi's men sitting in third place.
However, Choi knows that the likes of Mustafa Al Bassas and Bruno Cesar will pose a threat to Seoul's hopes of qualifying for their first Champions League semi-final.
"Al Ahli were a strong team as I expected," he continued. "They are a team with good individual skills and teamwork.
"Al Bassas is promising player and he will be the future of Saudi Arabian football, while Bruno Cesar is also a splendid player who can control the game with experience and great finishing.
"But even though Al Ahli have a lot of good players, I believe that FC Seoul have many talented players and that we are well organised."
Vitor Pereira's men are unbeaten in their last five matches in all competitions, but have been held in both their league games since drawing with Seoul in August.
However, Ahli remain in second place in their domestic standings as they seek to go a step further in this year's Champions League.
The Saudi Professional League outfit were beaten 3-0 by Ulsan Hyundai in the final last time out.
|Coach: Yong-Soo Choi|
for Il-Lok Yun 75'
for M. Molina 79'
for D. Damjanović 90+2'
|MLS Review: DC United deny nine-man Revolution, Rapids break drought|
|Bielsa hints at Marseille departure, congratulates Ligue 1|
|Silva, Matuidi eye fourth trophy|
|Jonas deserved golden boot - Jorge Jesus|
|Primeira Liga Review: Benfica celebrate title with home win|
|Ligue 1 Review: Monaco seal final Champions League spot, Marseille take fourth|
|Ancelotti to take sabbatical if sacked by Real|
|Mancini annoyed by ´absurd´ Inter mistakes|
|Simeone hails ´incredible season´|
|Replacing Xavi will be impossible - Luis Enrique|
|Ronaldo hopes Ancelotti will stay|
|Guardiola: We´ll be back stronger|
|Paris Saint-Germain 3 Reims 2: Cavani double sees champions celebrate title with routine win|
|Garitano stands down following Eibar relegation|
|Genoa 3 Inter 2: Kucka strikes blow to visitors´ Europa quest|
|Real Madrid 7 Getafe 3: Ronaldo nets treble and Odegaard makes history|
|Southend United 1 Wycombe Wanderers 1 (aet, 7-6 on penalties): Last-gasp Pigott and Bentley the hero|
|Odegaard becomes Real´s youngest player|
|Gargano omitted from Uruguay Copa America squad|
|La Liga Review: Depor save themselves with stunning comeback at Barca|
|Barcelona 2 Deportivo La Coruna 2: Salomao saves visitors as Xavi bids Camp Nou farewell|
|Granada 0 Atletico Madrid 0: Atleti secure third as hosts survive|
|Juventus 3 Napoli 1: Champions turn on the style|
|Tearful Klopp struggled to say goodbye|
|Scottish Premiership Review: Rangers to meet Motherwell in play-off final|
|Bundesliga Review: Freiburg and Paderborn relegated|
|Borussia Dortmund 3 Werder Bremen 2: Dortmund seal European spot as Klopp says farewell|
|Bayern Munich 2 Mainz 0: Schweinsteiger nets as champions celebrate title|
|Championship play-off final Preview: Karanka and Neil eye swift ascent to Premier League|
|Volland commits to Hoffenheim|
|Monk: Michu likely to move on|
|Allardyce not interested in Newcastle revenge|
|Sherwood confident of Benteke Villa stay|
|Rodgers calls on Liverpool fans to support Sterling|
|Khedira ´frozen out´ by Real|
|Hamstring injury rules Suarez out of Deportivo clash|
|Former Southampton managers hail ´excellent season´|
|Mourinho wants to remain in England after Chelsea|
|Rodgers ´150 per cent sure´ his job is safe|
|Maldini would ´love´ to help Milan|
|Doyle set for Rapids debut versus Whitecaps|
|MLS Review: Champions end winless run on day of late drama|
|Jemez doubted Rayo future|
|Zenga could replace Mihajlovic - Osti|
|Blanc wants to avoid Chelsea-like finish|
|Menez happy in Milan|
|Sherwood: Vlaar wants to stay|
|Arsenal v West Brom: Wenger calls for focus|
|Porto 2 Penafiel 0: Danilo scores in farewell game|
|La Liga Preview: Eibar, Almeria hoping for final-day salvation|
|Eredivisie play-offs: Go Ahead suffer surprise defeat, NAC win|
|South Africa warm up for COSAFA Cup with victory|
|Rodriguez will be like a new signing - Adkins|
|Renard leaves Ivory Coast role amid Lille speculation|
|Howedes doubtful for start of next Bundesliga campaign|
|Deschamps: Pogba and Evra will be happy to face Albania|
|Everton v Tottenham: Pochettino eyeing fifth spot|
|Crystal Palace v Swansea City: Pardew admits to talent envy|
|Van Gaal confident of keeping De Gea|
|Spurs to support Adebayor over family issues|
|Manchester City v Southampton: Koeman expects no favours from hosts|
|Chelsea v Sunderland: Champions set to finally lift trophy|
|Mancini: Inter need quality|
|Van Gaal: No favours for ex-United captain Bruce|
|Leicester City v QPR: Ramsey expects doomed Rangers to show pride|
|Koeman expecting quieter close season|
|Hughes delivers positive update on Bojan|
|Advocaat considering Sunderland offer|
|Hull City v Manchester United: Bruce accepts survival is tall order|
|Stoke City v Liverpool: Rodgers keen to move focus away from Sterling|
|Allardyce won´t let us down, says Bruce|
|Berahino can leave for top-four club - Pulis|
|Aston Villa v Burnley: Sherwood wanting win ahead of cup final|
|Big clubs would be making a ´mistake´ signing Bolasie|
|Peterborough announce Robertson as new manager|
|Relieved Sherwood eager to kick on|
|Newcastle United v West Ham: Carver dreading ´unbearable´ drop|
|Pellegrini unsure over Milner future|
|I am not good enough to win treble every year - Guardiola|
|Luis Enrique refuses to be drawn on Barca future|
|Ntep handed France call-up|
|Allegri compares Juve to class of 2003|
|My future to be decided on Monday - Allardyce|
|Ancelotti expects to stay at Real despite speculation|
|Play-off finals to go ahead despite discovery of World War II bomb|
|Mourinho lauds ´legend´ Lampard|
|Milan v Torino: Shadow of Ancelotti hangs over Inzaghi|
|Speroni extends Palace contract|
|Ramsey issues QPR warning|
|Valverde signs new Bilbao contract|
|Welbeck could miss FA Cup final and England double header|
|League One play-off final Preview: Preston hoping to end hoodoo|
|Rodgers expects Sterling talks to resume|
|Martinez dismisses Oviedo exit talk|
|Neil hoping to draw on previous play-off success|
|Cisse weighing up offers from USA, India and Poland|
|Hazard announced as Premier League´s Player of the Season|
|United should sign Cech if De Gea leaves - Scholes|
|Copa Libertadores Review: Cruzeiro draw first blood away from home|
|MLS Preview: Wondolowski poised for 100-goal club|
|Ligue 1 Preview: Monaco, Marseille, Saint-Etienne battle for Champions League spot|
|Bundesliga Preview: Relegation battle set for dramatic end, Dortmund to farewell Klopp|
|Serie A Preview: Radu in doubt for crucial Rome derby|
|Stankovic denies talk of Inter return|
|Benitez would be ´happy´ to manage Real - agent|
|Newcastle not expecting favours from Allardyce - Carver|
|Lacazette can be ´world class´ - Houllier|
|Hodgson defends Sterling|