Tottenham face Liverpool at Anfield this Sunday, looking to maintain momentum from their midweek Champions League win - but what's been behind their early-season struggles?

Spurs thrashed Red Star Belgrade 5-0 on Tuesday, with Harry Kane and Heung-Min Son both scoring twice and Erik Lamela completing the rout. But is the result a turning point or a brief high in a prolonged slump?

We have a very tough game on Sunday and hopefully we can take this momentum into that. Harry Kane

Spurs have been below par for much of the campaign and recent defeats at Leicester and Brighton, and embarrassing losses to Colchester United and Bayern Munich, have raised questions over whether last season's Champions League finalists are on the decline.

Have Spurs peaked? We examine the stats...

League form decline

We're just nine games into the 2019/20 Premier League season but Spurs are already 13 points behind leaders Liverpool and five points off the top four.

Arsenal, Manchester United and Chelsea are each facing problems of their own but the graphic below suggests Spurs peaked in 2016/17 - when they finished as Premier League runners-up to Chelsea - and their success under Pochettino has followed an arced path in decline.

That picture also rings true with their match-by-match form.

The graphic below shows their rolling five-game average for goals scored (in green) and goals conceded (in red), revealing their current state is only really comparable to Pochettino's first year at the club - and is far weaker than where they were a couple of seasons ago.

During my five years, it has all been praise for Tottenham... Ups and downs happen... The most difficult was the first season. Then there were a few seasons that were tough in some periods but I am so relaxed. Mauricio Pochettino, speaking after Leicester defeat

So what's behind the drop-off?

Problems in attack

Spurs have scored fewer goals per game in four successive seasons now, down from their peak of 2.3 per game in 2016/17 to just 1.7 this season.

The xG returns reveal an even more dramatic decline, plummeting from a 1.7 high to just 1.1 this term. And that pattern applies to shots on target, too.

Tap or click on the interactive headers to view stats

One of the most stark dips among the stats in the interactive graphic above is for big chances created. Spurs have come up with just nine all season. Out of all clubs in the Premier League, only Crystal Palace have mustered fewer.

It is no coincidence that deficiency has arisen in the wake of Christian Eriksen's dip in form. The Dane has been key throughout his time at Spurs - but now, alarmingly, there is no natural successor on the books.

Forward distribution

Spurs have been hovering around an average of 60 per cent possession over the past five seasons - although this also follows the recurring pattern of peaking at 62 per cent in 2017/18 and declining this term.

However, to maintain that share of the ball, Spurs have increasingly retreated in possession. Last season, compared with the previous campaign, Pochettino's side attempted 30 more passes in their own half per game but 40 fewer in the opposition's half.

New signing Giovani Lo Celso has been sidelined through injury, but has never recorded more than four assists in a league season in Europe

Even more striking was a sudden drop in the number of passes played into the final third. They registered 20 fewer per game which amounted to a 25 per cent drop.

Tap or click on the interactive headers to view stats

Defensive frailties

Unfortunately, Spurs' slump cannot only be attributed to a decline in goals, creation and distribution. Defensively, an equally damning inverted pattern emerges.

Tottenham are currently conceding 1.4 goals per game - exactly the same ratio recorded in 2014/15, with their most watertight season coming in 2016/17.

It could be worse. Spurs are currently facing 5.8 shots on target per game, more than any previous campaign under Pochettino.

The Argentine praised his team's successful pressing after their emphatic victory over Red Star. But much has been made of Tottenham's waning press recently.

As the interactive graphic below reveals, Spurs have recorded far fewer interceptions and duels won in recent seasons, an area their upcoming opponents Liverpool excel at.

Tap or click on the interactive headers to view stats

Transfer troubles

However, unlike many of their rivals, Pochettino has been severely restricted in the transfer market during his five years in London with a staggeringly low £3m net spend. That's a stark contrast to the £596m splashed by Manchester City during the same period.

Despite a record spend this summer, new recruits typically were ones for the future, such as Ryan Sessegnon, Jack Clarke and Tanguy Ndombele, and the limited financial outlay for transfers and wages has led to an ageing spine and wantaway stars.

Eriksen, for so long Spurs' chief creator, is running down his contract for a summer move, centre-back pairing Jan Vertonghen and Toby Alderweireld also have expiring deals, while the futures of Danny Rose and Serge Aurier are far from certain.

Whether Spurs can begin to reverse those issues in January remains to be seen. But more immediately they must deal with the challenge of Premier League leaders Liverpool.

Will the win over Red Star be a season-defining catalyst? Or will Liverpool expose Tottenham's underlying problems once again?

You can watch Liverpool vs Tottenham live on Sky Sports Premier League from 4pm this Sunday; Kick-off 4.30pm