Tomorrow's FA Cup tie will be the first time these two sides have met since 2005, but they'll become very familiar with each other by March, having been scheduled to play three times over the next three months due to Chelsea's Club World Cup commitments. Still, it seems likely this will be a different Southampton side to their usual Premier League eleven, as Nigel Adkins will have one eye on the club's battle with relegation and will rotate accordingly.
That makes it difficult to identify a starting XI for the hosts, although Nigel Adkins' will presumably keep with the 4-2-3-1 formation that has served them well in recent weeks. Adkins is a likeable manager who preaches proactiveness and an entertaining brand of football, but after their open strategy proved extremely costly earlier in the season, he's had to compromise towards a more structured approach.
Now, there is more focus on organisation and defensive discipline, with the wide players dropping deep to provide protection to the full-backs. Previously, the wingers - Adam Lallana in particular, who will be absent this weekend - would play high up the pitch and overload opposition full-backs, which worked to good effect in their biggest win of the season against Aston Villa.
The by-effect of this was that Southampton's fullbacks were constantly overloaded by sides that played with good width, and costly defeats against Everton and Arsenal prompted Adkins to switch to a more conservative system.
Now, the ‘free' player is the central attacking midfielder, normally Uruguayan Gaston Ramirez, a talented, direct dribbler also capable of playing on either flank. As a central winger, Ramirez drifts across the pitch to try and create chances, although he's also capable of breaking into goalscoring positions, as Arsenal found to their cost.
One face will be recognisable to Chelsea fans - Jack Cork has enjoyed a good run of games in the Southampton side as a tidy, energetic partner for the combative Morgan Schneiderlin. The latter is equal first for tackles in the Premier League, and third for interceptions, meaning he wins possession more than any other player. Southampton in fact records the most turnovers of any side in the league, so expect this to be a scrappy, physical contest punctuated by moments of flair.
Benitez will be aware of Southampton's tenacious qualities and might elect for the defensively secure presence of Jon Obi Mikel, provided the Nigerian is available for selection. After controversially rotating the side midweek, one expects Eden Hazard and Juan Mata to return to the starting eleven, and the diminutive playmakers will drift towards the flanks to find space away from the congested centre.