A place in the Round of 16 is up for grab for Al Ahli and Kashiwa Reysol, both of whom are aware a fourth straight win can book their early qualification with two games to spare regardless of the other results.
Leaders like Al Shabab, Esteghlal, FC Seoul and Guangzhou Evergrande, though, must count on wins and other results going their way if they are to progress.
Join FIFA.com as we look into Tuesday’s and Wednesday’s showdowns on a matchday that reprises last week’s meetings.
Kashiwa Reysol-Suwon Bluewings
There is little obvious evidence which can explain Suwon's 6-2 home collapse against Group H leaders Kashiwa last week. The K League giants – two-time winners in 2001 and 2002 before the reformation into the Champions League - have maintained their impressive domestic form, including seeing off Daegu FC 3-1 on Saturday to move to the top of table.
But last week’s loss to Kashiwa put their Asian campaign in jeopardy, raising coach Seo Jungwon's concern over the team's mentality after they inexplicably missed three out of four spot-kicks. With merely two points from three outings, Suwon know that only a win can revive their fast-diminishing hopes.
Hosts Kashiwa are, meanwhile, hoping to continue their unstoppable form against K League sides, having thrashed Jeonbuk both home and away in their continental debut last year. And Nelsinho Baptista's charges are keen to maintain their perfect record this year, with a fourth straight win enough to complete their qualifying mission. The Emperor Cup holders enter the return match-up on the back of a 3-3 draw against Nagoya Grampus Eight, with striking sensation Masato Kudo twice on target.
In the other group match, second-placed Central Coast Mariners travel to Guizhou Renhe on the back of their 2-1 first-leg home win, hoping to keep their place in the top two with a second victory.
The other attractions
The scenarios in Group A are such that leaders Al Shabab can advance with victory at Tractor Sazi, provided El Jaish don't lose against bottom side Al Jazira. The Saudi champions will look to in-form striker Nassir Al Shamrani, who grabbed the only goal in their last meeting. Al Jazira, meanwhile, must count on last year's top-scorer Ricardo Oliveira to rediscover his free-scoring form if they are to salvage a first win.
Nothing will, though, be decided in Group B, where Lekhwiya travel to Tashkent hoping to consolidate their lead with a second win against Pakhtakor. Despite suffering a 1-0 loss at Bani Yas on the home front, Al Shabab Al Arabi can take heart from their solitary-goal defeat against Al Ettifaq.
While a home win against Sepahan is enough to take Group C leaders Al Ahli through, it is the visitors that arrive at Riyadh with a 3-1 defeat of Naft Tehran, a result which saw the Iranian champions return to the top of the local standings. Al Gharafa, meanwhile, welcome Al Nasr confident of a third successive win.
Group D's Al Hilal face a daunting task at Esteghlal, with the Tehran giants able to seal qualification with a second home win, provided Al Ain don't lose at Al Rayyan in the other game. Despite a goalless draw at Al Ahli Dubai recently, the UAE champions can look to their formidable attacking duo of Asamoah Gyan and Alex Brosque.
Group E's top-two sides enter the matchday with lacklustre results on the home front, with leaders FC Seoul drawing Ulsan by 2-2 and Jiangsu Sainty losing 1-0 at Beijing Guoan. However, the K League champions know victory at Vegalta Sendai will see them through if Jiangsu also defeat hosts Buriram United.
The same can be said of Group F frontrunners Guangzhou Evergrande, who can advance with a third win at Muang Thong United should Jeonbuk also gain three points against Urawa Red Diamonds. Marcello Lippi's side have saved energy heading into the re-meeting, having seen their league fixture against Guizhou postponed.
Group G is wide open, with three sides tied on five points. But hosts Beijing Guoan entertain Bunyodkor knowing they can edge closer to progression with a second triumph. Meanwhile Pohang Steelers are expecting to continue their winning form against pointless Sanfrecce Hiroshima, who lost to Yokohama F Marinos 3-1 in the recent J.League outing.
Player to watch
The new season has seen Dejan Damjanovic maintain his prolific form for both club and country. The towering forward is FC Seoul's top-scorer on both the home and Asian front, while he recently came off the bench to grab a crucial equaliser against England in last month's 2014 FIFA World Cup Brazil™ qualifier.
2 – The duo of Sanfrecce and Al Nasr are seeking their first points respectively, while both Al Ahli and Kashiwa have fixed their sights on early qualification.
What they said
"We are well-placed to advance, but Muang Thong are not a team to be underestimated. Nothing can be taken for granted until the last whistle," Guangzhou Evergrande coach Marcello Lippi
2013 AFC Champions League matchday 4 fixtures
9 & 10 April
Group A: Al Jazira-El Jaish, Tractor Sazi-Al Shabab
Group B: Al Ettifaq-Al Shabab Al Arabi, Pakhtakor-Lekhwiya
Group C: Al Ahli-Sepahan, Al Gharafa-Al Nasr
Group D: Esteghlal-Al Hilal, Al Rayyan-Al Ain
Group E: Vegalta Sendai-FC Seoul, Buriram United-Jiangsu Sainty
Group F: Muang Thong United-Guangzhou Evergrande, Jeonbuk Motors-Urawa Red Diamonds
Group G: Pohang Steelers-Sanfrecce Hiroshima, Beijing Guoan-Bunyodkor
Group H: Guizhou Renhe-Central Coast Mariners, Kashiwa Reysol-Suwon Bluewings