While the team looked solid in defence, Sir Alex Ferguson was forced into a halftime substitute further up the pitch.
Paul Scholes replaced a nonsensical Nani.
The Portuguese winger has often received criticism from United fans. His display against their bitter rivals proves his Old Trafford future remains in the balance.
Nani is the type of player who splits opinion down the middle.
Last season, the 25-year-old contributed 12 goals and 13 assists in 44 appearances across all competitions.
His stats were arguably better than Antonio Valencia, who posted six goals and 15 assists in 39 appearances across the board.
Valencia went on to win the Sir Matt Busby Award as the fans' player of the year. He was also voted the best performer by his club colleagues (via Yahoo! Sports).
There are many reasons why Nani doesn't get such recognition.
Against Liverpool, he posted another dismal performance. Before he was hauled off at halftime, only 65 percent of Nani's passes made it to his peers. This was the lowest percentage of all outfield players.
Nani also flitted in and out of his defensive duties. He was the only United player who failed to win a tackle. Patrice Evra had a tough task dispossessing Raheem Sterling and needed extra support.
When the ball surrounded the left-sided winger, he was often out of position. He either got too close to Evra without closing the opposition down or failed to support Robin van Persie in attack.
Too often, the ball bounced clear of defence and Nani slowed play down on the halfway line. He afforded Liverpool time to regroup and halted United's momentum with his indecision.
Moving forward with the ball should be Nani's main strength. Against Brendan Rodgers' side, he completed two successful dribbles and was dispossessed twice. He often cut inside towards the centre of midfield and surrendered to Liverpool's physicality.
United entered the match with one striker. Ferguson placed huge trust in his wingers to provide support, and the former Sporting Lisbon player simply didn't show up.
With Nani off the pitch, United improved slightly. Valencia headed the team's list of top performers. He showed desire and unstoppable power to earn his side a vital penalty.
If this sniff of a chance had fallen to Nani, would he have done the same?
As proceedings came to a close, the Ecuadorian filled in at right back. He showed defensive quality, commitment and forethought to provide his team with a chance of winning the match.
United need this type of player. They don't need an individual who isn't prepared to fulfill simple duties in one of the most-anticipated Premier League clashes ever.
Ferguson must now consider Nani's position at Old Trafford.
The Scot obviously weighed up selling him to Zenit St Petersburg this summer. A £25 million fee was rumoured before the deal collapsed over the winger's colossal wage demands.
Nani is yet to sign a new deal at United. Reports suggest he is holding out for £130,000 before committing his future (via The Daily Mail).
As the winger's poor form continues, one question must be asked: Does he offer value for money?
On the back of his performance against Liverpool, Nani could be backflipping his way out of Ferguson's plans for the future.
Do you think Nani should leave Old Trafford this summer? Let me know in the comments section or hit me up on Twitter.
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