Liverpool has been a let-down on its return to Europe's top competition after a five-year absence, but can still qualify as runner-up behind Real Madrid in Group B by beating FC Basel at Anfield on Tuesday.
That is one of three direct deciders for places in the last 16, with the most high-profile coming in the Italian capital where Roma hosts English champion Manchester City for second place in Group E on Wednesday.
Italian champion Juventus needs a point against already-qualified Atletico Madrid to advance in Group A, Sporting Lisbon or Schalke will join Chelsea in progressing from Group G, while Monaco and Zenit St. Petersburg meet for the right to go through from Group C.
First place — and a possibly easier last-16 game — is up for grabs in four of the eight groups while eight teams will drop into the Europa League by finishing in third place.
Given its record against English clubs in the Champions League, Basel is one of the last teams Liverpool would have wanted to face in a must-win game.
Basel has won its last four games against Premier League opposition in the competition — against Liverpool in their second group game in October, home and away against Chelsea last season and at home to Manchester United in 2011 to knock out the then-English champion. Basel has lost just once in nine games against teams from England in the Champions League.
Anfield is famous for its atmosphere on big European nights but a trip to Liverpool shouldn't be daunting for the Swiss team.
Liverpool produced a string of great performances at home last season on its way to a second-place finish in the Premier League, but its attacking spark has disappeared with the departure of Luis Suarez to Barcelona and an injury to fellow striker Daniel Sturridge.
A disappointing ninth in the Premier League, Liverpool's only points in the Champions League this season have come against Bulgarian team Ludogorets Razgrad.
Liverpool captain Steven Gerrard was rested for the 0-0 draw against Sunderland on Saturday, with the Basel game in mind.
Manchester City could be without arguably its best four players as it goes to Rome in search of a win the team requires to qualify.
Star midfielder Yaya Toure is suspended, top scorer Sergio Aguero is out with a serious-looking knee injury sustained on Saturday, while playmaker David Silva and captain Vincent Kompany are major injury doubts.
City is back in form, winning its last five matches in all competitions, but has never won in Italy.
Roma is level on points with City and CSKA Moscow, which plays first-place Bayern Munich away. Roma will qualify with a win.
Repeat for Juventus
Just like last season, Juventus finds itself needing a point to qualify in its final group game. It will be hoping for a different outcome this time.
A goal by Wesley Sneijder for Galatasaray eliminated Juventus last year but, 12 months on, Massimiliano Allegri's team is at home, where it is unbeaten in nine matches in European competition.
The Bianconeri could even snatch first place by winning by a margin of two goals or more. Lose, and Olympiakos will finish second with a win at Malmo due to its head-to-head record against Juve.
"Wednesday's match against Atletico Madrid is a very important match for the whole Juventus world," captain and goalkeeper Gianluigi Buffon said. "It's like a final."
Schalke or Sporting
Schalke coach Roberto Di Matteo needs his team to win and a favor from his former club Chelsea if Germany is to have four representatives in the last 16 for the second straight season.
Schalke heads to eliminated Maribor lying two points behind Sporting, which travels to already-qualified Chelsea.
Di Matteo, who guided Chelsea to its first Champions League title in 2012, has changed Schalke's formation and the new 3-5-2 system has proved effective. The team's last three matches were all big-scoring wins — 3-2 (Wolfsburg), 4-1 (Mainz), 4-0 (Stuttgart).
"We are investing a lot of time in the new system," defender Jan Kirchhoff said, "and it's beginning to pay off,"
Winner takes all
It is winner takes all when Monaco hosts Zenit — with first place in Group C on offer for either club if Bayer Leverkusen loses at Benfica. Monaco will also qualify with a draw.
Real Madrid is the only team with five wins from five games ahead of its home match against Ludogorets in Group B while Barcelona needs to beat Paris Saint-Germain to overhaul the French champions at the top of Group F.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)