Two totally different backgrounds; two massively contrasting personalities; two alternative ways of tackling the beautiful game.
Rafa?s first ever league defeat in England, as manager of Liverpool, was inflicted by Big Sam?s no-nonsense Bolton.
They have exchanged various un-pleasantries since, and Allardyce went on record at one point as saying about his managerial rival...
"Our relationship is on the bad side of average; he doesn't like me. We always used to batter Liverpool at the Reebok, but you can't help him whingeing and moaning can you? ?
Rafa once sarcastically commented that Barcelona were ?thinking of copying? Bolton?s style of play, so there?s clearly no love lost between the two men. We await the latest head-to-head with interest.
We?re going for a West Ham win to add to Rafa?s problems at the Bridge, but what do the pre-match stats ? and the bookies odds ? suggest?
1 Chelsea are unbeaten in their last 12 league clashes with the Hammer since a 1-0 defeat at Upton Park in May 2003 (W11, D2).
2 West Ham have managed only one win, and five points, from their last six matches.
3 Sam Allardyce's side have failed to win a match in which they have trailed this season, gaining just two points from losing positions (D2, L4).
4 They have also only earned two points from their six matches against clubs currently in the top half of the table.
5 Andy Carroll is expected to make his 100th career league start whilst Mark Noble could make his 200th appearance for the Hammers.
6 Chelsea's points tally of 26 is their lowest in the Premier League after 14 games of a season since Roman Abramovich bought the club in 2003.
7 They have failed to win in their last six Premier League matches, equalling their longest barren run in the Abramovich era.
8 Benitez is the second Chelsea manager under Abramovich to fail to win in his opening two matches in charge; the first was Avram Grant.
9 Fernando Torres hasn't scored in the league in 10 hours and 49 minutes since his goal against Norwich on October 6. What odds on him breaking his duck tomorrow lunchtime?
In general, the bookies are quoting a West Ham home win at a generous 3/1, whilst Chelsea are 10/11 to give Rafa his first victory. It?s 5/2 the draw.
Check out all the odds on Betway ? the official betting partners of football.co.uk