When Manchester United faced Burnley at Old Trafford in January of last year, an abject 2-0 loss left them fifth in the Premier League and a distant 30 points behind leaders Liverpool.
It was the eighth league defeat of a season which appeared to be descending into crisis. Ole Gunnar Solskjaer's future looked in doubt. Fans were becoming increasingly disillusioned. The gulf between Manchester United and their old rivals had never felt wider.
What a difference a year has made. On Tuesday, a 1-0 victory over the same opponent, this time at Turf Moor, sent Solskjaer's side above Liverpool and onto the Premier League summit. From trailing by 30 points to leading by three, it has been quite the turnaround.
Solskjaer has repeatedly played down the significance of topping the table at this stage of the season. "No one will remember the league table on January 12th," he said earlier this week. But the mood around the club is one of cautious optimism.
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"Why shouldn't Manchester United fans believe?" said Sky Sports pundit Gary Neville after the Burnley game. "There's an element of unpredictability and Manchester United could exploit that."
Is this a genuine title challenge or an illusory one? Sunday's trip to Anfield will tell us more. Defeat would make their stay at the top of the Premier League a brief one. Victory would give them a six-point cushion on the champions with nearly half of the season gone.
That context surely makes it the biggest game of Solskjaer's tenure so far.
A title challenge seemed an impossibility back in October, when Manchester United were stumbling through their worst start to a season since the David Moyes era.
But they have won nine games out of 11 since then. For all their ups and downs over the last year, they have in fact amassed more points than any other side in the Premier League in that timeframe.
It is no coincidence their improvement coincides with the signing of Bruno Fernandes, who has scored 19 goals and provided 14 assists in 31 Premier League appearances since his arrival from Sporting Lisbon a year ago.
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But there is now a sense of things coming together elsewhere on the pitch too. Eric Bailly has helped United keep four clean sheets in six games since returning to central defence alongside Harry Maguire. Paul Pogba has found some form alongside Fernandes in midfield. Edinson Cavani has added thrust and firepower up front.
Solskjaer deserves credit for marrying it all together but his next challenge is to prove he can take this United side to the next level. His capacity to do that will be measured by Manchester United's performances and results against top opposition.
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They have of course enjoyed some memorable victories in big games during his tenure.
Paris Saint-Germain were famously defeated 3-1 for a place in the Champions League quarter-finals in March 2019. Manchester City, Chelsea, Tottenham and Arsenal have all been beaten domestically
United's overall record in 26 meetings with their big six rivals under Solskjaer - 10 wins, seven draws and nine defeats - is a respectable one, but last week's Carabao Cup exit against Manchester City was their fourth semi-final loss out of four under the Norwegian and exposed familiar shortcomings when the stakes are high.
Solskjaer shrugged off talk a mental block after that game, instead highlighting the quality of United's opponents, but Sunday's trip to Anfield is a similar test. Manchester United have got themselves into this position, but can they take the next step? Can they prove their credentials against a side whose level they strive to match?
It is a formidable challenge. Liverpool's defensive options are depleted and they have failed to win their last three Premier League games in a row for the first time in three years. But they remain unbeaten in their last 67 home league games. Anfield is a fortress.
Sunday's visit comes almost a year to the day since United's last one, when goals from Virgil van Dijk and Mohamed Salah consigned them to a 2-0 loss which underlined Liverpool's superiority.
United still have plenty of work to do to close the gap. But their line-up that day included Brandon Williams, Andreas Pereira and Daniel James. The Premier League table is not all that looks different now.
Solskjaer has never beaten Liverpool but he will take encouragement from the fact he has taken points off them twice at Old Trafford. Last season, United were in fact five minutes from victory before Adam Lallana cancelled out Marcus Rashford's opener. The year before that, Solskjaer's team ground out a goalless draw.
You suspect Manchester United fans would take a similar result on Sunday. Anything to ensure they remain in top spot. Anything to prove that they are not in the position by accident - and that they are capable of staying there for a little while longer. Solskjaer's biggest test awaits.
Pitch to Post Preview - Liverpool vs Man Utd: Graeme Souness' big match verdict; plus: the likely XIs, injury news, and predictions
In a special Pitch to Post Preview Podcast we look ahead to Sunday's blockbuster between Liverpool and Man Utd at Anfield.
Sky Sports pundit Graeme Souness joins Peter Smith to discuss the big match, including why the hosts will be wary of their rivals and which players must stand up and deliver for their side.
We also get the latest team news and possible starting XIs from Sky Sports News reporters James Cooper and Vinny O'Connor, while football writer Lewis Jones - AKA Jones Knows - makes his Pitch for what will happen in the game.