The Blues took the lead when Eden Hazard capitalised on poor marking before cutting inside Steven Davis and powering a shot through the legs of keeper Fraser Forster.
Pierre-Emerick Aubameyang was back on target to set Arsenal on their way after 66 minutes, with a finish from almost on the goal-line after Canaries' keeper Tim Krul turned Nicolas Pepe's shot on to the post and the same player then struck the
Trailing 1-0 from the first leg in Spain, Bayern levelled the tie through Xabi Alonso's deflected free-kick. Atletico keeper Jan Oblak saved Thomas Muller's low penalty, before Antoine Griezmann coolly fired in an equaliser.
Fernandinho put City ahead just after the break after an error by Liverpool's otherwise heroic keeper Simon Mignolet. But two glaring misses from former Liverpool forward Raheem Sterling opened the door for Coutinho's late leveller.
Martinelli celebrated a dream Champions League debut by rounding thekeeper and putting his side ahead before Jesus fired in a superb strike after the break.
Barca's talisman bamboozled Juve's defence and left Buffon spinning with another expert dribble and finish 21 minutes from time, while Buffon's blushes were spared as Barca had another ruled out after thekeeper fumbled a simple low cross on
They were thwarted on numerous occasions by United keeper Andre Onana, and despite the urgings of the home support were unable to draw level a second time.
However, Liverpool regrouped and were level after 29 minnutes when Mohamed Salah thrashed a finish high past Gunners keeper David Raya at his near post after collecting Trent Alexander-Arnold's raking pass.
The home side ought to have taken the lead on seven minutes when Gautier Lloris, in front of goal with thekeeper out of commission, placed his finish straight at Carlos Soler, covering on the line.
The England keeper, playing because David Raya was ineligible against his parent club, dallied over a clearance and allowed a sliding Yoane Wissa to score.
And the contest was effectively over when Marcos Alonso scored at the far post via the legs of Middlesbrough keeper Brad Guzan 11 minutes before the break.
They have now lost back-to-back league games for the first time since Pep Guardiola took over in the summer, and are four points adrift of leaders Arsenal.
England's total first-half domination was emphasised when captain Harry Kane scored his eighth goal in his last seven appearances six minutes before the interval when Nigeria keeper Francis Uzoho allowed his 18-yard shot to slip in.
The 33-year-old, who has suffered a dip in form recently, then fired Newcastle's second penalty wide and once keeper Djordje Petrovic saved Matt Ritchie's spot-kick Chelsea had gone from the despair of contemplating defeat to the sheer elation
United keeper David De Gea, making his first appearance of the season after signing a new four-year contract following the breakdown of his move to Real Madrid, demonstrated his worth with fine saves from Danny Ings and Jordon Ibe.