The final set of Champions League group stage fixtures get under way this week.

While Manchester City and rivals United have already qualified for the knockout stages, both Liverpool and Tottenham still have work to do.

Here, Press Association Sport takes a look at some of the talking points heading into Matchday 6.

Get the calculator out – and an abacus

There are still places in the last 16 up for grabs – with the most complicated of conundrums set for Group C. Current group leaders Napoli, second-placed Paris St Germain and Liverpool, in third, can still all qualify. Red Star Belgrade are bottom, but could yet make it through to the last 32 of the Europa League. For Liverpool, they have to win to stand any chance of a top-two finish – victory by more than one goal will ensure qualification. However, if PSG beat Red Star Belgrade away, then Jurgen Klopp’s men will need a 1-0 triumph or victory by two goals or more, but other win margins will not suffice. If that was not enough of a complicated formula, should the game in Belgrade end as a draw, Liverpool will advance with any win because it would leave them, PSG and Napoli all on nine points – but the English club finishing first on the three-way head-to-head. Oh, and do not forget Red Star Belgrade will take third place if they win and Liverpool lose. Simple, eh?

Reds need Anfield to rock again

Whatever the permutations, Liverpool need to win to keep their Champions League hopes alive, that much we do know. Anfield has seen some memorable European nights down the years – and the home fans will need to be in full voice once again if Klopp’s side are to make the most of home advantage.

Earn your Spurs at the Nou Camp

Tottenham gave themselves hope of reaching the last 16 when they saw off Inter Milan at Wembley last time out. However, the task ahead for Mauricio Pochettino’s men is still a daunting one – win in the Nou Camp to make sure of progress. However, with Spurs currently second on head-to-head away goals, should they match points-wise, Inter’s result at home to already-eliminated PSV Eindhoven, then that would be enough to put the English club through behind Barcelona, who have already won the group.

Can City slickers get back in the groove?

Much was made of Manchester City’s first Premier League defeat of the season at Chelsea on Saturday – but manager Pep Guardiola continues to champion the “incredible personality” of his team, who are perhaps starting to show the weight of fighting on all fronts. Nevertheless, City are already sure of safe progress to the last 16 in the Champions League and can seal top spot in Group F when they host German side Hoffenheim.

United front in Spain

While seeing off a struggling Fulham side, who finished with 10 men, at Old Trafford on Saturday is not exactly something to write home about, it extended United’s unbeaten run to five games in all competitions since losing 3-1 at City. With qualification for the knockout stages already delivered, another positive result away to Valencia on Wednesday night for Jose Mourinho’s squad and things might not look so bleak after all. Well, maybe.