How have Liverpool climbed to the top of the Premier League?

Defending champions Liverpool are back on top of the Premier League after their 2-1 victory over Tottenham saw them replace Jose Mourinho's side.

The Reds were briefly top for two successive weekends in late October but their inability to put together back-to-back wins in a six-match unbeaten league run kept them off the summit.

But Jurgen Klopp's team have defied a significant injury list which still shows no signs of easing to establish a three-point lead over their rivals.

Here, the PA news agency's Carl Markham looks at how they have done it and what it means for the chasing pack.

Consistency of key players

Partly by design, partly due to necessity as injuries started to mount up, Klopp has relied heavily on nine key players. Left-back Andy Robertson has played every minute of all 13 Premier League matches so far, midfielder Georginio Wijnaldum has featured in every minute of the 12 games he has started, Roberto Firmino has started all 13, with Mohamed Salah 12, Sadio Mane 11, and, due to injuries, Alisson Becker, Trent Alexander-Arnold and Fabinho (all 10) and Jordan Henderson (nine) make up the core group.

Surprise success of academy graduates

With Liverpool's injury list topping 10 at one point - including two first-choice centre-backs Virgil Van Dijk and Joe Gomez and new signing Thiago Alcantara - the squad has been stretched to the limit and critics suggested they would not cope. However, Klopp's faith in youngsters from the academy was well-placed with 19-year-old central defender Rhys Williams - who was on loan at Kidderminster last season - playing in all six Champions League matches and barely putting a foot wrong in his Premier League debut against Spurs. Midfielder Curtis Jones, also 19, made his breakthrough last season but has grown with every game in this campaign to lessen the pressure on midfield. Caoimhin Kelleher, 22 last month, impressed as understudy to the injured Alisson Becker on his Champions League and Premier League debuts.

Salah's scoring spree

The Egypt international's goalscoring statistics continue to grow with his strike against Tottenham his 84th in 120 Premier League matches for Liverpool. He has taken over permanent penalty duties this season and that has helped him to 11 in 12 games, finding the net in two thirds of the matches he has played in with only Chelsea, Arsenal, Sheffield United and Brighton keeping him out. He has eight in his last 11 matches in all competitions.

Dio-goals Jota

Liverpool's September swoop for Wolves forward Diogo Jota took most by surprise and his £41million price tag could have been an added pressure, as was the prospect of displacing the club's famed front three. However, the Portugal international hit the ground running with a sequence of nine goals in 12 matches - including a Champions League hat-trick against Atalanta - with Klopp not afraid to play all his four attackers in the same game, before a knee injury curtailed Jota's progress.

Benefits of having a proven style of play

The loss of Van Dijk was seen as the death knell for Liverpool's chances of defending their title just because of the influence he had last season and the subsequent loss of Joe Gomez and Joel Matip's persistent injury problems left Klopp without a senior centre-back. The German was criticised for leaving himself short, having let Dejan Lovren leave in the summer, but he adapted. Midfielder Fabinho has dropped back and been paired with the likes of Rhys Williams and Nat Phillips, who also made his Premier League debut this season, players schooled in the same system and tactics. Liverpool have had nine different starting centre-back partnerships in 13 matches and seven in the last nine. yet their 19 goals conceded includes seven at Aston Villa. With the front three almost taking care of themselves and the virtual omnipresence of Wijnaldum in midfield, incoming players have been able to slot in with very little adverse effect.

Where do they go from here?

There is still some way to go on the injury front with Jota and Kostas Tsimikas sidelined for the best part of two months and Van Dijk and Gomez unlikely to play this campaign. However, with Alex Oxlade-Chamberlain fit again for the first time this season, Thiago set for a January return and James Milner possibly back before the end of the month the situation could look even better heading into 2021. Klopp could still be tempted to look for centre-back cover in January but he has confidence in his back-up options in most departments.