Pep Guardiola rocked old foe Jose Mourinho as Premier League leaders Manchester City extended their perfect start with a 2-1 win at Manchester United, while Liverpool crushed champions Leicester 4-1 on Saturday.

City manager Guardiola inflicted the first defeat of Mourinho's United reign and collected his eighth win in 17 encounters with his nemesis in a pulsating encounter at Old Trafford.

Guardiola's side took the lead in a sweet moment of revenge for Kevin De Bruyne, acrimoniously sold by Mourinho when the pair were together at Chelsea, as the Belgium midfielder punished Daley Blind's uncertainty to slot past David de Gea in the 15th minute.

Kelechi Iheanacho doubled City's lead in the 36th minute when he tapped in after a De Bruyne shot hit the post and rebounded to the Nigeria forward.

A blunder from City's debutant goalkeeper Claudio Bravo allowed United to reduce the deficit in the 42nd minute when he dropped a cross and Zlatan Ibrahimovic pounced to lash home.

But City held firm in a frantic second-half despite more nervous moments from Bravo, whose studs-up lunge on Wayne Rooney could have drawn a penalty and a red card.

Guardiola has now masterminded four successive Premier League wins since arriving from Bayern Munich in the close season and his team sit three points clear of third-placed United and second-placed Chelsea, who travel to Swansea on Sunday.

"We're happy. These guys have a heart. In the first-half we were better and won a lot of duels against a physically stronger team," Guardiola said.

"In the second-half, the long balls, you just pray because it's almost impossible to control that."

Mourinho added: "I had two or three players in the first-half that, if I know what is going to happen, I don't play them. This is football and sometimes players disappoint managers. It's my fault because I'm the manager."

In front of the biggest Anfield crowd since May 1977, 53,000 fans watched Liverpool mark the unveiling of their extended main stand with a ruthless demolition of Claudio Ranieri's champions.

Roberto Firmino opened the scoring with a clinical finish in the 13th minute and Sadio Mane increased Liverpool's advantage with a close-range effort in the 31st.

Liverpool midfielder Lucas, playing out of position in central defence, gave Leicester a lifeline with a terrible 38th-minute backpass that Jamie Vardy drilled into the empty net.

But Adam Lallana's rocket in the 56th minute and Firmino's second in the 89th minute wrapped up Liverpool's second win of the season and left Leicester contemplating a lacklustre start to their title defence.

"It was a good challenge because we can be really strong, but Leicester have big quality and we had to show we believed in our style. It was a good performance in a wonderful place," manager Jurgen Klopp said.

At the Emirates Stadium, Arsenal left it late to ease the pressure on Gunners boss Arsene Wenger, who has been questioned over his transfer dealings and the team's slow opening to the season.

The critics were sharpening their knives when Arsenal fell behind in the 18th minute through a Petr Cech own goal from Dusan Tadic's free-kick.

But Arsenal equalised 11 minutes later thanks to a spectacular overhead kick from Laurent Koscielny.

And Santi Cazorla secured Arsenal's second win of the season when the Spaniard stroked home a controversial penalty awarded for Jose Fonte's tackle on Olivier Giroud in the 94th minute.

"It is a relief because we missed many chances and they had one or two opportunities having thrown everything forward," Wenger said.

Tottenham swept to a 4-0 victory at bottom-of-the-table Stoke as South Korean Son Heung-Min sparkled on his first appearance of the season.

Son volleyed Tottenham in front just before half-time and netted again with a fine finish from 16 yards in the 56th minute.

Dele Alli bagged Tottenham's third and Harry Kane sealed the rout with his first goal of the season in the 70th minute.

Watford staged a superb recovery to beat West Ham 4-2 and secure Italian manager Walter Mazzarri's first win since taking charge in the close season.

The Hammers looked in control after Michail Antonio scored with a pair of headers in the fifth minute and 33rd minute at the London Stadium.

But Odion Ighalo netted for Watford in the 41st minute, Troy Deeney equalised in first-half stoppage time and second half goals from Etienne Capoue and Jose Holebas sealed the points.

Crystal Palace won 2-1 at Middlesbrough, Bournemouth beat West Bromwich Albion 1-0 and Burnley drew 1-1 with Hull.