BARCELONA, Spain (AP) -- Fresh from its domestic demolition of Real Madrid, Barcelona will be aiming to advance to the Champions League knockout rounds for a 12th straight year when it hosts Roma on Tuesday.
The terrorist attacks in Paris, however, continue to cast a long shadow over European football, and Barcelona has announced increased security measures at Camp Nou, as have other stadiums across the continent.
Madrid, Manchester City and Zenit St. Petersburg have already locked up their spots among the final 16. With two games left, 27 of the remaining 29 teams are still in contention for the other 13 places.
Arsenal is among those on the brink of elimination. To avoid an exit, Arsene Wenger's side needs to beat Dinamo Zagreb and hope Bayern Munich defeats Olympiakos in Group F on Tuesday.
Here are some things to know about this week's matches:
An in-form Barcelona only needs a point to win Group E.
The defending European champions can still wrap up qualification even if they lose to Roma, as long as Bayer Leverkusen doesn't win at last-placed BATE Borisov.
Roma drew 1-1 against Barcelona in their first meeting.
Madrid has already advanced, but coach Rafa Benitez and his players are under intense pressure to win at Shakhtar Donetsk on Wednesday.
Madrid has lost two straight games in the Spanish league and fans called for Benitez to be fired after its crushing 4-0 loss at home to Barcelona on Saturday.
"I am worried about restoring my team's spirits," Benitez said.
Madrid can win Group A with a victory in Ukraine. Paris Saint-Germain will qualify from the same group with a win at Malmo.
PSG's match away to Malmo on Wednesday would normally have been a celebration of Zlatan Ibrahimovic's return to the Swedish club where he scored the first goal of his glittering career, way back in 1999.
Instead, his mind is still very much on last week's attacks in Paris, which cost the lives of 130 people and injured hundreds more.
"(There is) news all the time," the 34-year-old Ibrahimovic said. "It's difficult to focus."
PSG's players returned to domestic duty on Saturday, wining 2-1 at Lorient, but their celebrations were very much muted.
"I'm a Parisian and I grew up in Paris, I was touched as a lot of people were," said midfielder Blaise Matuidi. "Now we have to try and move forward, to enjoy playing, even if it's difficult for everyone. We know life may never be the same as it was before, but you have to deal with it."
Displays of solidarity with France have been overwhelming in recent days, with English fans singing the national anthem, and a lone pianist playing La Marseillaise at Madrid's Santiago Bernabeau stadium before the game against Barcelona.
AS PSG captain Thiago Silva puts it: "Everyone's a little bit French now."
SECURITY IN ST. PETERSBURG
Russian authorities have stepped up security ahead of Zenit's home game against Valencia on Tuesday in Group H, with body searches for fans.
St. Petersburg is reeling from the Oct. 31 crash of a Russian airliner in Egypt which killed all 224 people on board, many of them from the St. Petersburg area. Russian authorities have said the plane was brought down by a bomb.
CITY TARGETS 1ST PLACE
Manchester City may have already qualified for the knockout stage, but its job is only half done.
In the past two seasons, City has finished second in its group and been drawn to play Barcelona in the last 16, losing on both occasions.
Eager to avoid another top team in the knockout state, City is targeting top spot in Group D, meaning manager Manuel Pellegrini will likely play his strongest possible team at Juventus on Wednesday.
Manchester United can advance by beating PSV Eindhoven at Old Trafford on the same night in Group B, and Chelsea could also progress with a win at Maccabi Tel Aviv on Tuesday, depending on the result of the Porto-Dynamo Kiev game in Group G.