Just one week into the season and already the Premier League has served up what could be a season-defining clash.
Liverpool, the reigning champions, looked lethargic and were slow to get out of the blocks as they battled their way to a 4-3 victory over newly-promoted Leeds.
Meanwhile Chelsea, who have spent big in the transfer window in a bid to give Frank Lampard the tools to mount his own title challenge, overcame their own blip on Monday to secure a 3-1 win over Brighton.
With both holding lofty ambitions, but failing to fully convince on the opening weekend, it is an opportunity for both to restate their case for being considered genuine contenders.
Here, Sportsmail looks at the areas on the pitch that could define Sunday afternoon's encounter.
Frank Lampard and Jurgen Klopp will see their sides go head-to-head once more on Sunday
Timo Werner can make Reds rue their failed pursuit
For a long time, it seemed for all the world that Timo Werner would become a Liverpool player this summer.
However, a charm offensive from Chelsea and dithering on Merseyside means the Germany international lines up in Blue on Sunday as the pair prepare to meet at Stamfrod Bridge.
While Jurgen Klopp already possesses a formidable frontline, Werner could still make his compatriot regret his club's hesitancy when it came to a move.
Werner looked sharp on his competitive debut - latching on to a mistake at the back to win his side their penalty from which Jorginho opened the scoring.
It was his second outing at the Amex Stadium, his first in a pre-season friendly saw his first strike in Chelsea colours.
He provides a focal point up front that Frank Lampard's side sorely lacked last year, with the out-of-favour Olivier Giroud eventually muscling his way back into the fold such was their dearth of options up top.
Werner now has a chance to cement that place as his own, and will have been heartened to see just how badly Liverpool's defence struggled with newly-promoted Leeds last weekend.
The 24-year-old scored 78 goals in 127 league appearances for RB Leipzig, and you sense it won't be long until he is off the mark at Stamford Bridge. Scoring against the Reds would be extra-sweet for the striker, too.
Timo Werner could have been a Liverpool player, but ended up joining Chelsea this summer
Virgil van Dijk has lost his aura of invincibility
For the past two seasons no defender has had a more intimidating aura surrounding them than Virgil van Dijk.
The glowing praise from pundits, team-mates and supporters, not to mention the personal awards, has been continuous for the Dutch stopper, who proved so instrumental in Liverpool's 2019-20 title success.
However, last Saturday, a certain shine came off his usual polished performance. There was the trademark bullet header at the other end to put his side in front, so his aerial presence is not in question.
But it was his actions at the other end that caused concern, most notably his uncharacteristic mistake which allowed Patrick Bamford to steal in and level for Leeds at Anfield to make it 2-2.
It was symptomatic of an unconvincing display by Klopp's defence, with the reigning champions surrendering three goals to a newly-promoted side.
Even more worrying is that the display was in keeping with Liverpool's woes in the second half of last season, where they produced a handful of sub-par displays as they eventually wrapped up the title.
Having seen Werner pounce on mistakes and make Brighton pay on Monday night, eyes will be drawn to see how Van Dijk reacts to his opening day disaster.
Virgil van Dijk did not look at his formidable best during Liverpool's opening day encounter
Blues could be vulnerable down the flanks
While the Reds looked vulnerable last Saturday, Chelsea have their own frailties, too.
Brighton gained a lot of success down the flanks on Monday night, with Tariq Lamptey impressing against his old club down the right-hand side.
His pace caused Marcos Alonso no end of problems, and it was down the Spaniard's wing the chance came for Lewis Dunk to equalise at 2-1.
They allowed 15 crosses in total, something they may wish to avoid replicating on Sunday.
With both Trent-Alexander Arnold and Andrew Robertson two of Liverpool's most potent threats, the Blues will have to be alert to the danger from Klopp's two full-backs.
Leeds attempted to quell the danger by overloading on the flanks, crowding out both the England and Scotland internationals in a bid to negate their threat.
A similar tactic may be thought upon by Lampard after his wide defenders' limitations were shown up by a side tipped to struggle this season.
Tariq Lamptey caused Chelsea full-back Marcos Alonso a few problems down the right flank
Liverpool will cause problems from set pieces
One thing that was clear from Liverpool's opening day performance; they know how to make the most of a good set piece.
Three of their four goals came from dead-ball situations - Van Djk's opener, Salah's second and the second penalty was the result of a corner that just was not dealt with properly.
Liverpool are a tall team, the likes of their Dutch centre back and Fabinho can cause havoc in the air, and it is something Lampard's men must be aware of.
It has been a growing concern at Chelsea, too, with the club conceding 14 times from set pieces last season - only six sides conceded more.
Organisation will be key then if the Blues are to keep Klopp's men at bay, but that may be easier said than done when Liverpool possess one of the top dead-ball specialists in the country in the form of Trent Alexander-Arnold.
Chelsea are all too aware of it as well - with the England full-back having notched twice against them previously from a free-kick.
The Reds were a threatening force at set pieces, with three of their goals coming from them
Defending could be an afterthought
Let's be honest. Without trying to jinx it, this clash has goals written all over it.
The pair served up seven goals between them on the opening weekend and looked far from convincing in defence.
Add on to that a reminder of the scoreline the last time these two met, a scintillating 5-3 encounter as Liverpool celebrated their title success in style, and it's difficult to see a clean sheet for either side.
Both excel at playing on the front foot, and will do so to their detriment at times - Liverpool failing to stem the flow when being battered by Manchester City towards the end of last season, while Chelsea were on the end of some thumping defeats in Europe at the hands of Bayern Munich.
With neither side worrying about missing any of their top attacking stars, it could be another forgettable afternoon for defences at Stamford Bridge.
Liverpool and Chelsea shared eight goals during their encounter at the end of last season
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