If Sheffield United are to upset Liverpool in Saturday's lunchtime encounter, a week after securing a 2-0 win over Everton, then Oliver Norwood will be key.
Before I explain why, we should highlight how the 28-year-old midfielder got to where he is now.
It is a journey worth admiring. Before this season, Norwood had never played in the Premier League - despite being promoted to it three times.
In 2016-17, he helped Brighton out of the Championship, then was moved on before he could make his top-flight debut.
In 2017-18, he helped Fulham out of the Championship, then was moved on again. In 2018-19, he made it a hat-trick of Premier League promotions. He helped Sheffield United out of the Championship and this time, he was not moved on.
As his manager Chris Wilder later joked: 'That would have been a bit cruel, wouldn't it? To say, "Thanks, Ollie, cheers, now there are a couple of Championship clubs that might want you…" I think he was dreading that phone call from me throughout the summer.'
Wilder recognised what he can bring to his team and Liverpool will be aware of that on Saturday, too. Norwood is so crisp in possession. In all of the Premier League, only Jorginho has hit more passes into the final third than him.
The 28-year-old drops deep, gets the ball then hits it into the channels. Normally, those passes are meant for his wing-backs, but George Baldock and Enda Stevens could be a bit preoccupied at Bramall Lane on Saturday.
The hosts will play a back three but as Liverpool's full backs - two machines in Trent Alexander-Arnold and Andy Robertson - push up, that could become a back five.
No side has produced more crosses than Liverpool's 146, with a league-high 61 coming from Alexander-Arnold, so Wilder's wing-backs should drop deep to help their defence.
Norwood will be ratting around at the back, too, but he will look to get his head up whenever he gets the chance. He will fire those diagonal balls of his into the channels for his strikers to chase instead.
There will be space there if Alexander-Arnold and Robertson are stationed high up the pitch, so Liverpool's centre backs will have to beware that. They should prepare themselves for a few long ball battles at Bramall Lane, too.
I mentioned how Norwood has produced the second-most passes into the final third in the Premier League. The player who has produced the third most? United goalkeeper Dean Henderson.
They aren't afraid to test centre backs like that, so Virgil van Dijk will have his hands full. Only one centre back in the Premier League has won more aerial duels than the Dutchman and he will be wearing red and white on Saturday – Jack O'Connell.
Keep an eye on him from set-pieces. Wilder will relish pitting his wits against Jurgen Klopp on Saturday.
Like Norwood, he worked hard to get to where he is now. He was named the LMA's League Two manager of the year in 2016, then League One manager of the year in 2017, then Championship manager of the year in 2019.
Now in the Premier League, he is trusting in his system. It took down Everton last week. Now he has his eyes on the other half of Merseyside.