London - Premier League leaders Liverpool face another stiff test of their title credentials when they travel to third-placed Chelsea on Saturday defending a perfect record from their opening six league games of the season.
Chelsea have only dropped two points themselves under new coach Maurizio Sarri and beat Liverpool at Anfield 2-1 in the League Cup on Wednesday.
Here are three key battles that could decide the outcome at Stamford Bridge on Saturday.
Alonso has been one of the keys to Chelsea's flying start with his rampaging runs providing goals and assists from left-back, prompting Sarri to claim the Spanish international may be the best player in his position in Europe.
However, even Sarri admits Alonso still needs to work on the defensive side of his game.
Arsenal exploited the space down Chelsea's left in scoring twice and missing a host of other chances in an early season five-goal thriller and West Ham should have beaten The Blues when Andriy Yarmolenko headed wide a great chance having escaped Alonso's clutches in a 0-0 draw last weekend.
Salah returns to Stamford Bridge seeking to show Chelsea the error of their ways in letting him leave two years ago.
The Egyptian has failed to match the stunning form of his 44-goal debut season at Liverpool so far this campaign, but still has three goals in six Premier League games and looked sharper in a 3-0 cruise past Southampton last weekend.
Salah is still not a man you want to offer space to and unless Alonso curbs his own tendency to rampage forward, Salah could prove deadly on the counter-attack.
Liverpool boss Jurgen Klopp hailed Sarri's rapid overhaul of Chelsea's style in just a few months from the caution of Antonio Conte to a side that dominate possession.
Jorginho's decision to follow his former boss from Napoli instead of joining City has been crucial to that transformation.
The Brazilian-born Italian international has completed well over 200 more passes than any other midfielder in the Premier League this season including a league record of 180 against West Ham.
However, Jorginho will not be given time to settle into his normal rhythm against Liverpool's midfield pressing, no more so than the in-form Milner.
The 32-year-old has shown incredible energy levels to disrupt the flow of other possession-dominant sides like Tottenham and Paris Saint-Germain to quickly win the ball back and feed Liverpool's prolific front three.
In a chaotic summer off the field for Chelsea, their best move in the transfer market was ensuring Hazard did not follow Belgium team-mate Thibaut Courtois in heading to Real Madrid, despite suggesting after the World Cup such a move appealed to him.
Hazard has kicked on from his stunning performances in Russia, where he was named the second best player at the World Cup, scoring six times including an incredible solo run and finish to win the League Cup tie between the two in midweek.
Yet, Sarri has demanded even more, believing Hazard can match Salah's goal-scoring feats of last season if he concentrates his energies more on playing in the final third than dropping deep to try and create.
Alexander-Arnold has impressed in a far more solid Liverpool defensive unit than last season and kept Neymar quiet in the win over PSG. But on current form stopping Hazard will be an even tougher test for the 19-year-old.