Liverpool host Manchester United in the fourth round of the FA Cup this weekend and will be looking to continue their good form after seeing off Manchester City in the second leg of the Carling Cup semifinal in a closely-fought encounter.
Liverpool will be focusing on cup success this season; they have, at best, an outside chance at a Champions League spot, and winning a cup would guarantee their place in the Europa League next season.
Qualification for the League Cup final will do nothing to diminish their desire to progress further in the FA Cup, especially when their opponents are none other than archrivals Manchester United.
All of the 22 players on the field will have vital roles to play, as well any substitutes, but Steven Gerrard could well be the key to the tie.
The 31-year-old midfielder has long been Liverpool's talisman, and they have clearly missed him during his injury spells this season, as they have in the past.
Gerrard can run a game from central midfield, even against the best oppositions. Few players can match his poise on the ball, his passing ability and his ball winning skills. These are all skills that Liverpool will need to take full advantage of if they are to see off a Manchester United side that, although not at its strongest, is nothing to laugh at.
For a recent example, look no further than his return to the starting lineup against Manchester City in the first leg of the Carling Cup semifinal. Gerrard's distribution immediately made Andy Carroll look like a different, far more threatening player and his presence allowed Liverpool to control the midfield for much of the first half.
Whether or not Andy Carroll starts remains to be seen, but if he does, Gerrard will be the one to provide him with the type of balls that made him so deadly at Newcastle. If he doesn't play, Gerrard will still be an important provider of chances for the likes of Dirk Kuyt and Craig Bellamy.
Either way, Gerrard is a vital part of Liverpool's attacking play.
Against a Manchester United side that has shown some defensive frailties this season, Gerrard is the perfect player to exploit any weaknesses, just as he did against Manchester City and Stefan Savic.
Manchester United also look a little under strength in central midfield. Paul Scholes could start in the middle of the park, and the United legend has not been at his best since coming out of retirement. He has yet to play to the level at which he was playing in the years leading up to his retirement, although he will get there in time.
This potential weakness in midfield is something that Gerrard will pounce upon without mercy. If Liverpool can limit the amount of possession United have and keep them stuck in their own half, they will be in with a fantastic chance of making it to the fifth round.
Gaining control of the midfield will make it hard for United to get Antonio Valencia into the game, something that makes Gerrard even more important for Liverpool.
Valencia has been in fantastic form for Manchester United during the last few games and his runs down the wing and balls into the centre could well be United's primary offensive tool. If Gerrard and his midfield colleagues are able to disrupt Valencia's supply, United will see one of their best tactics for scoring thwarted—something that can only help Liverpool succeed.
Who will come out on top on Saturday?
It is not just Gerrard's footballing ability that make him so important to the outcome of the FA Cup clash; his mental attributes must also be considered.
Gerrard is a big-game player. Who led the comeback charge against AC Milan in 2005? Who popped up to win the FA Cup for Liverpool in 2006? Who scored against United early this season?
The answer to all these questions is Steven Gerrard.
This is partially down to his immense ability, but it is also down to his state of mind. Steven Gerrard is a man who likes to be in a scrap, who likes to go down guns blazing. That is exactly what Liverpool need against Manchester United, because they will go into the biggest game in English football as underdogs.
It is an attitude that not only brings out the best in Gerrard himself, but also in his teammates. Seeing your captain, a club legend, giving it his all is exactly what could be required if Liverpool find themselves in danger of losing the tie. Gerrard's presence will ensure that Liverpool never give up, just as the presence of players like Paul Scholes and Ryan Giggs does for United.
Gerrard is also the type of player who can get the crowd behind him with just a few touches of the ball, and with the match taking place at Anfield, the crowd will play an important role. Players like Steven Gerrard will need to ensure that the crowd does not let the noise dip; quieting the Kop will only encourage United to play better.
With all that has been going on recently with regards to Luis Suarez and Patrice Evra, the atmosphere inside Anfield is sure to be particularly partisan.
The players will be fired up, and tempers could flare. Steven Gerrard's reaction to this atmosphere will be vital. If he does not keep his teammates calm and keep the peace whenever a poor tackle or dubious call is made, the game could boil over and the players will have a hard time focusing.
Quite clearly, Gerrard is not going to win the game by himself. Liverpool are far from a one-man team and they have several players who could produce stand-out performances. Gerrard is not going to be able to run the midfield all by himself and his efforts must be matched by his teammates.
However, if Steven Gerrard doesn't perform, Liverpool are going to be hard pressed to beat Manchester United, even with home-field advantage. He is a vital cog in Liverpool's wheel and a poor performance from him will inhibit their ability to create chances, retain possession and rise to the occasion.
Liverpool should fear a bad outing from Steven Gerrard as much as they should hope for a good showing.