Aston Villa presents a tactical challenge as well as the usual worries Chelsea may have, such as Fernando Torres' form.
With Chelsea next, three is magic number for Aston Villa
With the Chelsea fans almost as restless as Roman Abramovich, the club's owner, every game is a test for Rafa Benitez, but Sunday's Premier League fixture against Aston Villa presents a tactical challenge as well as the usual worries about the reaction of the crowd and the form of Fernando Torres.
Villa are unbeaten in five games in the league and in the last two of those games - and in the Capital One Cup quarter-final against Norwich City - have played with a back three.
It is not uncommon for teams to select an additional centre-back against Stoke City, giving themselves extra insurance against the long-ball approach. So well did Chris Herd, Ciaran Clark and Nathan Baker - none of them older than 23 - perform that Paul Lambert, the Villa manager, stuck with the system for the trip to Norwich.
That brought a 4-1 win and, while Villa were perhaps a touch fortunate to survive the opening half hour at Liverpool last week, they came away with a 3-1 victory.
"Those three have been brilliant of late, they really have," Lambert said.
What makes Sunday's meeting particularly intriguing from a tactical point of view is that when Chelsea have faced a back three this season, they have struggled.
That was most obvious against Juventus in the Uefa Champions League.
In the home game, Eden Hazard's unwillingness or inability to close down or track Stephan Lichtsteiner meant the Swiss wing-back was able to isolate Ashley Cole again and again.
In Turin, Kwadwoh Asamoah, the left wing-back, who had been largely kept quiet by Ramires at Stamford Bridge, was far more involved in attack and laid on the second goal for Arturo Vidal. The warning signs had been there on the opening day of the season and the away game at Wigan Athletic, although they were largely overlooked because Chelsea scored twice in the first 10 minutes so the game was over almost before it had begun.
But after that opening burst, Wigan repeatedly worked Emerson Boyce and Maynor Figueroa into space in wide areas and got crosses into the box.
Although the early goals made it feel like a comfortable Chelsea win, Wigan actually had 18 shots to their 10.
The vulnerability of a 4-2-3-1 is always in that area between the full-back and winger and wing-backs naturally operate in that area.
Chelsea, though, cannot afford to give them space and playing against a back three offers Benitez an opportunity to prove he is a better tactician than the man he replaced, Roberto Di Matteo.
Do that often enough, quieten the doubters in the crowd, and Benitez may be a serious contender to take the Chelsea job full-time next season. And, as he acknowledged, there are always other options.
"My future?" he asked. "I know things, but I am not going to say anything about Real Madrid, because I believe that I should not.
"We are talking about two very high-level teams.
"I have a challenge and that is trying to win and do good things, it's a matter of time in convincing many people.
"If we are successful it will be easier to convince them. I'm very calm."
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