Where would Manchester United be this season, without Robin Van Persie? Probably, there or thereabouts near the top, but nowhere close to being seven points clear from nearest rivals Manchester City.
Where would Liverpool be without Luis Suarez? Most likely near the relegation zone, looking to climb their way up into the top half of the table.
The two strikers' impact is unquestioned. And when Manchester United meet Liverpool in, traditionally, the biggest game of the season, one of the two will most probably have the final say.
In the fixture at Anfield, it was Van Persie who put the nail in Liverpool's coffin, burying a late penalty to give United all three points. That match was way back in September; Van Persie had already started to show his importance to his new side, while Suarez was just hitting his straps in what is proving to be his best season yet in the English Premier League.
Having said that, there are ten other players on either side looking to etch their own names on this historic tie.
Another major factor that could decide the match either way is the decisions made by the referee - in this case Howard Webb.
Webb is easily the most high-profile referee in the English game and has stood in the World Cup final as well as the Champions League final. He is a capable referee, but Liverpool fans have been on the end of some poor decisions made by him on a few occasions in the past, particularly in this fixture.
Webb's biggest job will be to be as invisible as possible, and let the players on the pitch take the spotlight.
"When you go into a game you hope you don't get a bad break against you, maybe one that isn't justified," Sir Alex Ferguson said.
"The referee has to make a decision in a split-second. He doesn't have the benefit of watching a replay.
"It happens so quickly these days that it is very difficult for referees to pick them right all the time. That's all I'm going to say about it. We want it to be a good game. Over the years Manchester United v Liverpool games have been relatively free of controversy."
In September, however, United, after going a goal down, got lucky with Jonjo Shelvey sent off harshly, and a soft penalty awarded, which Van Persie duly dispatched.
Liverpool manager Brendan Rodgers is hoping lightning doesn't strike twice.
"We hope we don't have the decisions go against us that went for United," he said. "In the first game a sending off and penalty cost us the game. I hope they don't get decisions that can influence the results.
"I believe Howard Webb is a very good referee, well established in the Premier League and who has refereed a World Cup final. I'm confident the game will be decided on quality and not a referee's decision."
United will be without Wayne Rooney, but Nani and Anderson are expected to feature after a lengthy absence.
Liverpool will welcome back Fabio Borini, after the forward missed nearly three months of action with a broken foot, but defender Jose Enrique is ruled out.
United are the favorites for this game, and rightly so. The fact that they are playing at home at Old Trafford will play a big part, but when it comes to Derby games, form and predictions more often than not go out the window.
One safe prediction can be made, though. Van Persie and Suarez will sparkle, and the striker who performs better on the day might just decide the tie in his team's favor.
Expected lineups: Manchester United: De Gea; Rafael, Ferdinand, Vidic, Evra; Carrick, Cleverley; Valencia, Kagawa, Young; Van Persie.
Liverpool: Reina; Wisdom, Skrtel, Agger, Johnson; Lucas, Allen, Gerrard; Sturridge, Suarez, Sterling.
Prediction: 3-2 to Manchester United
