Mertesacker tells Arsenal to prove title credentials
Arsene Wenger's side head to Eastlands still reeling from a 2-0 defeat against Napoli on Wednesday which could prove a fatal blow to their hopes of winning the Champions League.
The Gunners needed just a point to finish top of their group and secure an easier draw in the last 16, but instead they slumped to second place and will now face either Barcelona, Bayern Munich, Real Madrid, Paris Saint Germain or Atletico Madrid.
It was a major setback just days after a frustrating 1-1 draw against Everton stopped Arsenal opening up a seven-point lead at the top of the Premier League.
In the circumstances, another defeat against City, who have won all seven of their home league matches and scored 29 goals in the process, would be a disaster heading into the busy Christmas programme.
And Germany centre-back Mertesacker knows the critics are once again starting to question whether Arsenal have the mental strength to overcome the psychological scars of the club's eight-year trophy drought.
"Now everybody is questioning our group and asking if we can maintain that level, so we have to stay together and think that 'yes, we are strong enough'," Mertesacker said.
"It is always difficult, especially after 15 games in the league and with the Christmas period coming.
"You think you have a good chance to achieve something this season, but you have to keep your momentum and that is really important."
While Arsenal hope to cement their position at the top, fourth-placed City can't afford to lose their 100 percent home record if they want to stay in touch with the leaders.
Manuel Pellegrini's team are already six points behind Arsenal thanks to some disappointing results on their travels and England midfielder James Milner concedes this weekend's match will have a major influence on City's hopes of regaining the title they won in 2012.
"With the gap Arsenal have at the top, if they win or we win, things are going to look very different, so it is important we get the victory," Milner said.
"There are so many games in December, and if you look at the league table going into that month, it always looks completely different when you come out of it into January.
"It is important that it looks a lot better than it does now for us."
Elsewhere, second-placed Liverpool, five points behind Arsenal, travel to Tottenham with goalkeeper Simon Mignolet demanding his team-mates step up in the absence of inspirational captain Steven Gerrard.
England midfielder Gerrard will be missing with a hamstring injury and Mignolet said: "We have other leaders in the team as well.
"We have a decent enough squad to deal with injuries, to cope with those kind of things.
"Every game we go into hopeful of getting three points. We will go to Tottenham and be positive."
Jose Mourinho repeated his call for more goals from his strikers ahead of third-placed Chelsea's meeting with Crystal Palace.
Mourinho's side are five points adrift of the Gunners following last weekend's surprise loss at Stoke and they were less than impressive again in a midweek win over Steaua Bucharest.
Demba Ba got the winner against Steaua but Mourinho has demanded more from the Senegal striker, who has just three goals in all competitions this season.
"Could get more," said Mourinho of Ba. "He has two goals in the Champions League, which is nice for him. More goals in the Champions League than in the Premier League."
Manchester United, without a win in their last four league matches and 13 points behind Arsenal, have no margin for error as they head to Aston Villa on the back of two successive league defeats.
United manager David Moyes has come under fire for his role in the champions' struggles, but winger Ashley Young insists the players should shoulder their share of the blame.
"Of course. We are the players who go out on the pitch," Young said when asked whether they felt responsibility should be shared.
"Everyone is in it together; manager, staff and players. We win together, we lose together."
Saturday (1500GMT unless stated)
Cardiff v West Brom, Chelsea v Crystal Palace, Everton v Fulham, Hull v Stoke (1730GMT), Manchester City v Arsenal (1245GMT), Newcastle v Southampton, West Ham v Sunderland
Aston Villa v Manchester United (1330GMT), Norwich v Swansea (1330GMT), Tottenham v Liverpool (1600GMT)
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