Five things we learned in the Premier League

Manchester City's Argentinian striker Sergio Aguero (2ndR) celebrates scoring the opening goal from the penalty spot, marking his 177th goal for the club, during the English Premier League football match between Manchester City and Burnley at the Etihad Stadium in Manchester, north west England, on October 21, 2017. AFP PHOTO

What you need to know:

Everton may have spent some £150 million ($198 million, 168 million euros) on new players during the last transfer window but a big outlay has never been a guarantee of instant success and a 5-2 loss at home to Arsenal left the Toffees in the relegation zone.

Manchester City went five points clear at the top of the Premier League after their 3-0 win at home to Burnley was coupled with a shock 2-1 loss for Manchester United against Huddersfield.
Tottenham maintained their title challenge with a 4-1 win against Liverpool at Wembley while, in more bad news for Merseyside, Arsenal added to the growing pressure on Everton manager Ronald Koeman with a 5-2 away victory that sent the Toffees into the relegation zone.
Here are five things we learned in the Premier League this weekend:

Mourinho pays for halting United momentum
Heading into their game at Liverpool last weekend, Manchester United were flying, their six wins in seven Premier League games - and 21 goals -- leaving them joint-top with Manchester City. But despite Liverpool's struggles, manager Jose Mourinho opted for a cautious approach that saw his side come away from Anfield with a goalless draw. They've not looked the same team since. After toiling to a 1-0 win against Benfica in the Champions League, United came crashing to earth in an error-strewn 2-1 defeat at promoted Huddersfield Town. Mourinho slammed his players' attitude afterwards but, having gambled with his team's momentum, he also shares responsibility for the gap between United and City.

Aguero back in the groove
Just 23 days after suffering a broken rib in a car crash in Amsterdam, the Manchester City forward Sergio Aguero claimed claimed a record-equalling strike in the leaders' 3-0 win over Burnley on Saturday. When Aguero was injured following the taxi accident it was initially feared he would be sidelined for several months, but the Argentinian recovered quicker than expected and made his first start since then to help shatter Burnley's stubborn resistence. The 29-year-old equalled Eric Brook's City goalscoring record with a 30th minute penalty as he put Pep Guardiola's side ahead with his 177th goal for the club.

Liverpool defence needs urgent work
Jurgen Klopp admitted it himself after Liverpool’s 4-1 thrashing at Tottenham Hotspur – his team’s defending was “bad, bad, bad” and it is only getting worse. Having been overwhelmed 5-0 by Manchester City last month, Liverpool have conceded more goals at this stage of the season (16) than at any time since 1964. With the January transfer window a long way away, Klopp must school his current defenders on the training ground if Liverpool's hopes of a top-four finish –- let alone a title challenge –- are to survive the English winter.

Batshuayi Chelsea's unlikely hero
With 19 minutes left at Stamford Bridge on Saturday, Chelsea were on the verge of a third successive league defeat as Watford held onto a shock 2-1 lead. It was the kind of dire situation that prompted Chelsea fans to pray for a moment of magic from Eden Hazard or Alvaro Morata, but instead it was the much-maligned Batshuayi who rescued the Blues. Meeting Pedro's cross with a bullet header, Batshuayi bagged Chelsea's crucial 71st minute equaliser 10 minutes after coming off the bench and scored again in stoppage-time to seal the points after Cesar Azpilicueta got the third. In a matter of minutes, the Belgian striker, often criticised for his poor performances, had gone from zero to hero, keeping his team's title defence afloat in the process.

Money not buying Everton success
Everton may have spent some £150 million ($198 million, 168 million euros) on new players during the last transfer window but a big outlay has never been a guarantee of instant success and a 5-2 loss at home to Arsenal left the Toffees in the relegation zone. New players need time to gel together but now the question the Everton board must decide is whether former Southampton manager Koeman is still the right man to oversee that process. A shout of "Taxi for Koeman" from the crowd at Goodison Park during Sunday's loss did not bode well for the Dutchman's future on Merseyside.