Manchester City and Napoli are the two most prolific teams in Europe's five major leagues, making Tuesday's Champions League encounter at the Etihad Stadium a genuinely mouth-watering prospect.

Pep Guardiola's City average 3.625 goals per league game and their 7-2 rout of Stoke City on Saturday made them the first team to amass 29 goals in the first eight games of an English top-flight season since Everton in 1894.

Prior to their 1-0 win at Roma on Saturday, Napoli had scored at least three goals in each of their first seven league games, their tally of 25 goals in those matches establishing a new Serie A scoring record.

With the two sky blue sides flying high at the top of their respective championships, AFP Sport explains why they are finding the net with such frequency.

Cast of match-winners sets City soaring

City manager Guardiola spent the close season addressing problems in his defence, but the upshot has been that his team are now able to exert total dominance over their opponents.

With new full-backs Kyle Walker and Benjamin Mendy (until he succumbed to injury) helping to pin opposing teams high up the pitch, City's dazzling array of midfielders and strikers have been able to make hay.

Sergio Aguero, Gabriel Jesus and Raheem Sterling have each scored seven goals in all competitions and Leroy Sane six, giving City a multi-faceted menace reminiscent of Guardiola's great Barcelona and Bayern Munich teams.

Their key player is Belgium international Kevin De Bruyne, whose vision, impeccable technical quality and pinpoint passing make him one of the most dangerous attacking midfielders in Europe.

"He is one of the best players in the world," Jesus said of De Bruyne after the Belgian laid on two goals in the demolition of Stoke.

"His quality is outstanding as an individual out on the pitch, but it's the way that he makes that work for the whole team, and connects with the other players, that makes him special."

Guardiola has experimented with a 3-5-2 formation, which lets him pair Aguero and Jesus up front, but his team have played their most devastating football in the 4-3-3 system he used last season.

They have scored 24 goals in their last five league games, larruping Liverpool 5-0, walloping Watford 6-0, crushing Crystal Palace 5-0, stuffing Stoke 7-2 and pulling off a highly impressive 1-0 win at champions Chelsea.

Scholarly Sarri sparks Napoli goal rush

Napoli coach Maurizio Sarri has created one of the deadliest attacks in Europe, with 26 goals scored in eight Serie A games.

"He (Sarri) really is a genius. He sees things others don't see," says Senegalese defender Kalidou Koulibaly.

The spark for the Napoli revolution was the sale of Gonzalo Higuain to Juventus in July 2016.

An injury to Poland's Arkadiusz Milik, coupled with Manolo Gabbiadini's inability to take Sarri's tactics on board, resulted in Belgian winger Dries Mertens having to reinvent himself as a striker.

It proved a stunning success as Mertens finished last season with 38 goals in all competitions and he has continued this term with seven in eight league games.

The brilliant Mertens is supported by Jose Callejon (four goals) and Lorenzo Insigne (three), with Brazilian Allan adding vital thrust from midfield.

"He's a scholar. He makes you understand how football is and isn't unpredictable. In short, with Sarri football is maths," said Koulibaly.

Guardiola has called Napoli "one of the most beautiful teams in Europe" with Arrigo Sacchi praising "the emotion, the show".

"Sarri is a great conductor, who's given his team a precise identity and a love of playing," said Sacchi, who orchestrated AC Milan's unprecedented run of success at home and in Europe in the early 1990s.

"It's not a club with an immense history, but Sarri is doing an extraordinary job.

"Their play lights up, guides, it shows personality and gives character to those who don't have any. It makes them grow."