The Reds have won nine league games in a row to move to the top of the Premier League table, with City four points behind—but with two matches in hand. Victory, then, is vital for the Reds if they want to keep their title hopes in their own hands.
Brendan Rodgers has changed tactics game to game as required, but the same 12 or 13 players have played in each of the most recent matches. The defence looked largely stable until the game at West Ham United last week, when Mamadou Sakho came in for the injured Daniel Agger.
Though Agger is fit and available again, as per LiverpoolFC.com, Rodgers should give serious consideration to keeping Sakho in the side for the visit of the third-place team, with his particular brand of abilities more suited to dealing with City's attack.
Mobility and Power
Liverpool might have the two best forwards of the league season on their team in Luis Suarez and Daniel Sturridge, but there is no argument that Manchester City's Sergio Aguero is one of the very best on the planet—when he's fit.
He is, however, expected to return to face Liverpool after missing the last eight league games. In fact he's only played twice in the Premier League since mid-December, meaning he is far from guaranteed to start, per PhysioRoom:
What Aguero brings to the side is ceaseless movement, a fantastic appreciation of space on both sides of the defensive line and the ability to change direction quickly while in possession. While Agger's reading of the game is good and he certainly isn't afraid to put himself into challenges, Sakho can boast the better agility and acceleration as a centre-back, and is not just coming off the back of an impact injury as Agger is.
Edin Dzeko is perhaps the likely starting option for City in attack, known for both his aerial threat and his power as well as his ability to get across the first defender to the near post.
Martin Skrtel and Sakho are both strong aerially—as evidenced last week against West Ham. And although Agger was, until recently, statistically the top Liverpool centre-back by percentage of headed duels won, his form in that regard dipped significantly over the last few weeks, winning less than half of his duels in his last six appearances.
Sakho is also a far more proactive defender, stepping out of the line to intercept the ball before the strikers are able to take possession; this as much as anything could be a big step toward keeping the visiting attack quiet at the weekend, though it is also a risky strategy to adopt too often.
Using the Ball
Agger is seen as a composed, cultured defender who can bring the ball out of the back line and into midfield, an important component in Rodgers' preferred method of structuring play from deep.
That's a true reflection of his game, but he has been eclipsed in his positive use of the ball this term by his team-mates.
Both Skrtel and Sakho have a better pass-completion rate than Agger, and Sakho plays more passes forward per 90 minutes on the pitch than the Dane—which is certainly not as a result of Sakho playing safe. Indeed, the French defender is often seen threading incisive passes into the midfield line at pace, yet regularly posts plus-90 percent figures for his completion rates.
He's also capable of bursting past an opponent at pace and opening up a gap in midfield to play into. Skrtel has been seen marauding up the field of late to good effect—something Kopites are more accustomed to seeing from Agger—but the No. 5 hasn't produced that side of his game enough this term.
The bottom line is, City have a phenomenal attack which Liverpool are going to have to be at their best to continually repel at the weekend, even though they'll certainly hope to cause City plenty of problems at the other end, too.
Who should start alongside Skrtel?
Simply put, Agger has had a handful of substandard performances recently, which led to calls from some quarters to restore Sakho to the team even before the West Ham fixture. Now that he has been given a run out, he'll be anxious to keep his place as he bids to earn a World Cup spot for France, too.
That won't worry Rodgers, who will just be concerned with which defender can best keep out the threats of Aguero, Dzeko and Co.
Both on the last couple of matches and on his defenders' capabilities over the course of the season, that points to Mamadou Sakho lining up alongside Martin Skrtel on Sunday.