Arsenal started the season strongly with a six-game winning streak that lifted them to second position in the league but have since faded and are seven points behind fourth-placed City with just two wins in their last six league games.
The 27-year-old Belgium international had joined City squad last week after helping his country progress to the World Cup semi-finals in Russia.
Arsenal goalkeeper Petr Cech has given an insight to the multinational shape of the modern Premier League by revealing he speaks to his defenders during matches in three languages.
Danny Welbeck, making his first appearance of the season as a late substitute, headed a stoppage-time winner to give Arsenal a 2-1 home win over league leaders Leicester City in the Premier League on Sunday.
Arsenal have only lost six times to Tottenham Hotspur in 43 matches since Arsene Wenger became their manager nearly 18 years ago, but the Frenchman is taking nothing for granted before the first north London derby of the season on Saturday.
Barcelona will put Manchester City to the sword if they commit the same kind of errors as they did in their Champions League encounter last month, coach Luis Enrique said.
Images from the English Premier League matches played on Sunday
Images from the English Premier League matches played on Sunday
IMAGES from the Europa League matches played on Thursday
Photos from the English Premier League match played between Manchester United and Arsenal on Saturday
Wenger dropped Rob Holding for the visit to Stoke, preferring Shkodran Mustafi alongside Nacho Monreal and Sead Kolasinac at the back.
Arsenal's dramatic 2-1 Champions League win against Anderlecht on Wednesday rescued three valuable points but the victory only served to paper over the ever-widening cracks.
Arsenal ended their away hoodoo against Premier League title challengers with a 2-0 victory at Manchester City on Sunday that left Chelsea five points clear at the top.
Images from the English Premier League match played between Arsenal and Crystal Palace on Monday
Sergio Aguero's hat-trick led Manchester City to a 3-1 win over Arsenal on Sunday and back into second place in the English Premier League, two points behind leaders Liverpool.
Napoli went down 3-1 at home to RB Leipzig, Arsenal and AC Milan enjoyed comfortable away wins, and Borussia Dortmund's Michy Batshuayi scored twice to secure a 3-2 victory in Europa League last 32, first leg action
Arsenal manager Arsene Wenger has risked angering frustrated fans by saying the under-performing London club do not need any January signings if everyone in the current squad stays fit.
Arsenal named a strong side captained by Mesut Ozil while Real had Bale on the bench and Eden Hazard, wearing the number 50 shirt, starting alongside fellow new signing Luka Jovic in attack.
IMAGES from the English Premier League matches played on Sunday
Arsenal suffered another painful Premier League defeat as Swansea City capitalised on some glaring errors to win 3-1 on Tuesday, boosting their survival hopes and denting the visitors' top four chances.
Lopetegui blends youth and experience in Spain World Cup squad
Spain coach Vicente del Bosque has called Atletico Madrid's Brazil-born forward Diego Costa into his squad for the first time for this month's friendlies away to Equatorial Guinea and South Africa.
Manchester City had to battle back from behind to earn a 1-1 draw against Premier League newcomers Wolverhampton Wanderers who gave the champions a real test at Molineux on Saturday.
A summary of Sunday's Premier League matches.
A Sergio Aguero hat-trick helped Manchester City get back to winning ways in the Premier League with a 3-1 victory over Newcastle United, as they stayed 12 points ahead of Manchester United who had to dig deep to secure a 1-0 win at Burnley.
Arsenal manager Arsene Wenger slammed his side's defending after watching Anderlecht claw their way back from three goals down to earn a 3-3 draw in Champions League Group D on Tuesday.
An Aaron Ramsey strike and a Kalidou Koulibaly own goal gave Arsenal a 2-0 victory over Napoli in the first leg of their Europa League quarter-final, while Chelsea beat a stubborn Slavia Prague 1-0.
Jose Mourinho's Chelsea turned from domestic whipping boys back to European stalwarts on Wednesday, beating his former club Porto 2-0 to top Champions League Group G.
Images from the English Premier League matches played on Sunday
Tottenham Hotspur brutally exposed Liverpool's defensive frailties as Harry Kane plundered two more goals in his side's 4-1 romp at Wembley on Sunday.
Real Madrid earned their first-ever win over Liverpool with a wondrous Cristiano Ronaldo goal spearheading a 3-0 Champions League victory at Anfield on Wednesday which appeared as classy as it was dominant.
News of all that's transpired on and off the football field
Coach Pep Guardiola was left thrilled after ManchesterCity revived their Champions League bid by beating his old club Barcelona 3-1 in a gloriously open Group C encounter at the Etihad Stadium on Tuesday.
Barcelona battled back from a goal down and scored twice in the second half to overcome hosts Borussia Moenchengladbach 2-1 in their Champions League Group C match on Wednesday despite the absence of the injured Lionel Messi.
