What is Manchester United's first-choice centre-back pairing?

In the next two weekends, Manchester United will face a couple of challenging Premier League fixtures -- home to Liverpool and away to Tottenham Hotspur -- and they should provide some insight as to whom Sir Alex Ferguson considers to be his first-choice center-back pairing. There are no other additional Premier League nor UEFA Champions League ties during the midweeks that precede or follow those ties so whomever the manager selects likely will hint at which players are currently preferred.

There is some context to be considered though as the players selected will not make them definitively first-choice. In the past year, Rio Ferdinand has done well to manage the ailments that hindered him in the recent past. However, since he's 34-years-old now, Ferguson has already indicated that he will try to avoid playing the former England international every four days as often as possible. His involvement will be carefully managed.

Prior to Nemanja Vidic's horrific knee injury thirteen months ago in Switzerland, he was genuinely a world-class defender and he was probably the world's best pure defender in the penalty box area. He's yet, though, to fully recover and despite an impressive performance recently versus West Bromwich Albion, the United captain has also shown signs of rust in recent weeks. Vidic, himself, has expressed caution just last week in regards to his recent return:

"The doctor is managing the games [I can play]. Over the first two or three months I have to really look at the games I can play because sometimes I might have a reaction. This is a process I have to go through."

- Vidic

Jonny Evans was tremendous last season and at 25-years-old, the general perception is that he's entering the prime years of his footballing career. Ferguson recently had this to say about the Northern Irish defender:

"He is the future. Nemanja [Vidic] and Rio know that. There is no doubt. His form is improving all the time. I think his experience helps. As he matures and gets experience year-by-year, he is getting better. There is no end to his improvement. He looks as if he is improving all the time. That, for us, is a great sign."

- Ferguson

Evans, though, is prone to making mistakes and this certainly irks some supporters. This is why some are hesitant to proclaim him one of the heirs to the great Rio/Vida axis. I would argue though, the extent of this lambasting is a bit over the top. He clearly is a talented center-back. It just may not be world-class talent.

Chris Smalling is a hugely promising prospect as well. He had a tremendous debut season at United in 2010/11 and he excelled in some big games during that season's run-in when Ferdinand was often injured. The 23-year-old, though, has battled a plethora of his own injuries in the past two seasons and this has hindered his development somewhat. It's also prevented him from establishing himself as a clear first-choice player during a time when Ferdinand and Vidic have succumbed to both age and/or injury.

Phil Jones, along with Smalling, has been tipped at times as the future of both United and England. The 20-year-old is quite versatile and this has actually resulted in him featuring more at either right-back or in central-midfield in the past two-and-a-half seasons at both United and Blackburn Rovers. Despite the England international's athleticism and bravery in aerial duels, there is some concern at the moment as to whether he's tall enough to regularly feature in central-defense. Jones definitely seems behind the other four right now in the pecking order at center-back.

With this in mind, it's clear that many players will see their name on the team sheet at center-back during the final ~five months of this season -- whether that is because of necessary rotation (especially for the older players), injury, and/or form. Who though, when everybody is healthy and in decent form, does Ferguson consider first-choice right now in central-defense. This weekend's match versus Liverpool is one of the few moments this season when the gaffer has had privilege of choosing between four or five healthy players. Whom will he choose as his center-back pairing? Here's a brief discussion of the most likely pairing options:

Rio Ferdinand/Jonny Evans

Evans seems most assured when paired with Ferdinand. These two have been the healthiest center-backs this season and due to them having the most consistent form at the moment, they appear most likely to start at the weekend. The duo compliment each other well, too, as Evans is comfortable stepping out of the back knowing that positionally sound Ferdinand is covering in behind.

Rio Ferdinand/Nemanja Vidic

This pairing was once the most dominant partnership in world football. Since that time though -- roughly between 2007-10 -- age and injuries have caused to both decline. This duo is possible to start together on Sunday because Liverpool ties are always nervy affairs. Perhaps Ferguson will seek experience. However, it seems more likely not to happen when considering that both are not as mobile as they once were. United would be extremely vulnerable to the movement and pace of Luis Suarez, Raheem Sterling, Suso, and Daniel Sturridge.

Jonny Evans/Chris Smalling

This could be the future of United's central-defense. Both players have good pace for the position and this enables Ferguson the flexibility to play with a high-line and with the comfort of knowing that both players are relatively capable of defending on the turn. The duo are both solid enough on the ball as well and this is important for United's preference to build-up attacking moves out of the back. This possible duo though, seems less likely than the previous two because it's hard to imagine Smalling being selected over Ferdinand, and possibly Vidic too, at this moment in time.

Jonny Evans/Nemanja Vidic

In theory, this pairing makes some sense: one is comfortable on the ball and capable of stepping into the midfield while the other is a hardened and dominant penalty box defender. The trouble with this pairing, though, is that the duo haven't worked together much in recent seasons. For that simple reason, it doesn't seem probably Ferguson would make this choice with the options at his disposal.

Nemanja Vidic/Chris Smalling

This pairing was very impressive at times in the early parts of 2011. It's hard to imagine though, that both of these players would be chosen over Ferdinand and/or Evans.