Should Liverpool and Jurgen Klopp stick with Roberto Firmino or twist with Diogo Jota?

In this four-part series, Telegraph Sport assesses a tactical or technical conundrum each of the four Premier League title contenders has to solve after the international break. Part one deals with Liverpool and part two Manchester United. Manchester City and Chelsea will be published on Friday.

As the league's top scorers and the only team still unbeaten after seven matches, Liverpool have a strong claim to be the most impressive of the four title challengers so far.

Jurgen Klopp's team have produced some slick and dynamic attacking play to rival the best of their back catalogue, boasting the highest expected goals figure in the division.

While not possessing Manchester City-levels of frugality, they have been solid enough defensively with Virgil van Dijk returning even if City gave them a chasing for 45 minutes at Anfield.

The question remains whether Liverpool can sustain this level over the course of 38 games in a season in which Premier League sides are likely to thrive in the Champions League and reach the latter stages. Their squad is the thinnest of the league's 'big four'. In microcosm, home draws with 10-man Chelsea and City hinted that Klopp's team might not have the same capacity to sustain their signature intensity across 90 minutes.

We might see greater variety in Liverpool's attacking combinations rather than Firmino, Sadio Mane and Mohamed Salah being ever-present. Mane and Salah will miss games early in the new year due to the Africa Cup of Nations, which will leave Liverpool reliant on the penetrative runs and box threat of Diogo Jota.

While there are ways to field all four attackers, Klopp's key selection decision will likely be whether to opt for Jota or Firmino and it could prove a case of horses for courses.

Firmino's general play may attract more plaudits than his end product, but he still finished last season with nine goals and seven assists in the league. According to FBref data, his combined expected goals and expected assists per 90 minutes was just 0.01 behind Mane, so the idea he does not offer threat has been exaggerated. There is no question though, that Firmino's value to Klopp lies in his ability to stitch play together, draw defenders out to create space for Salah and Mane and to press from the front.

Do Mane and Salah still score with Jota in the team?

Jota is an inside forward and scorer in the Mane and Salah mould, with additional aerial prowess, but is not thought to possess the collaborative qualities that have made Firmino so valuable. While Jota may offer more goals as an individual than Firmino, would his presence in the team blunt Mane or Salah, who could well be the best attacking player in the world just now?

Though the sample sizes are relatively small, that has not been the case when Jota as started ahead of Firmino. In eight Premier League games alongside Jota since the start of last season, Salah has five goals, four assists and has taken 32 shots on goal. Mane alongside Jota in those games has scored five, assisted one and taken 30 shots on goal.

In 23 games alongside Firmino since the start of last season, Mane has scored eight, set up four and taken 64 shots. Salah has scored 13 goals, got two assists and taken 79 shots. So on a per game basis, Mane and Salah's productivity has actually been higher alongside Jota than Firmino. We should be wary of the small number of games, and also bear in mind that Klopp has tended to go back to Firmino for matches against stronger opponents.

Where the argument may swing back in Firmino's favour is that Liverpool look a little light in central midfield this season, following the departure of Georginio Wijnaldum and then Harvey Elliott. Firmino's industry and ability to drop in and facilitate moves might become a more attractive option to Klopp if the likes of Fabinho, Jordan Henderson and Thiago Alcantara (Henderson and Thiago have had their own fitness problems) are being overwhelmed.

Alexander-Arnold playing inside and out

Another tactical feature to watch is how Trent Alexander-Arnold, back for Watford after a groin injury, is used in Liverpool's attacking phases. While Klopp was withering in his assessment of England using him in midfield, Liverpool have varied Alexander-Arnold's positioning in subtle ways this season. At times, like for this opportunity at Leeds, he is overlapping down the right and outside Salah in a familiar way:

In this move against Chelsea's resolute back five, Alexander-Arnold is on the ball inside Salah, with the Egyptian being the player to hold his width on the right instead:

Unlike his adversaries in the dugouts of title rivals, Klopp cannot change games from the bench so easily through the introduction of off-the-peg talent. Smaller tweaks and variations will be needed to keep Liverpool's legs and approach fresh enough to get through mid-winter.