Arsenal vs. Chelsea: What Has Changed Since the Teams Last Met?

Oct. 29, 2011 is the type of day that isn't easily forgotten. Eight goals has a tendency to do that.

So much has changed since then. Chelsea have changed managers (Roberto di Matteo calls the shots now, something Andre Villas-Boas, the 33-year-old Portuguese wonder-boy tactician and supposed heir apparent to Jose Mourinho as the next managerial master, was doing back in October), and they have changed formations.

Gone is the 4-3-3 favored by Villas-Boas, which had the back four playing a very high line (something Arsenal fans are all too familiar with, having seen their own defense use that tactic in many a game in recent years), replaced by the 4-2-3-1 di Matteo has used since taking the helm in early March.

Di Matteo comes across as a savvy fellow—no stranger to the English game (he played for Chelsea and managed West Browmich Albion from 2009-11, and was the assistant manager for the entire season up to Villas-Boas's firing), he believed Chelsea could get back to their best with a tactical switch-up.

Poof, gone was the 4-3-3 roundly used since Jose Mourinho's arrival in 2004-05, and in came a 4-2-3-1, which shifted playmaking maestro Juan Mata more centrally, where the Spaniard could play behind a lone striker—either Didier Drogba or Fernando Torres, depending on Di Matteo's preference that week.

Drogba was absolutely transcendent in Chelsea's midweek Champions League semifinal first leg, where the Ivorian hit man not only scored the lone goal in a crucial 1-0 win at Stamford Bridge, but burst his lungs on repeated occasions while tracking back and disrupting the vaunted Barcelona passing build-up game with well-timed intrusions and tackles.

(A certain Arsenal winger/striker out on loan in Russia might take note of the importance tracking back can play in a game.)

The news that Drogba is ruled out of Saturday's key clash because of a knee injury deals a massive blow to Chelsea's hopes. While I would not go so far as to say it casts a pall on the proceedings (a blue tint, if you will—mirroring Chelsea's home jerseys), given how good he was on Wednesday, it is a worry.

Drogba might well be called revitalized, but it is Torres who has benefited the most from a new manager. Seemingly out of sorts under Villas-Boas, the Spaniard had scored just four goals all season before Di Matteo's arrival.

In just his third appearance after the switch, Torres netted a brace against Leicester City, who while not the cream of the Barclay's Premiership crop, provided the 28-year-old Spaniard with confidence nonetheless.

That's not to say that Torres is a man reborn. At least, not yet. He's still shown a propensity to drift out of games, but it does appear that playing as the lone striker once again (his preferred position under Rafa Benitez at Liverpool) has improved his confidence.

Solomon Kalou is another player who, after months dwelling in Villas-Boas's sideline doldrums, where he had become surplus to requirements (he says it was over his expiring contract, hence he did not fit into the Portuguese's plans, who thus saw little use for him as he attempted to create his long-term project), has since become Chelsea's first choice on the wings, where his pace has once again caused problems.

Kalou has played in every one of Chelsea's last eight matches (five starts, three substitute roles).

The most important thing Di Matteo has done for Chelsea, however, is inspire confidence.

By the end of Villas-Boas's reign, the Blues looked listless, destined for a 2012-13 season without Champions League football—a byproduct of their foundering form in league.

Yet since March 4, the team that had won just one of its last seven (all competitions) has lost just once in 13 matches (all competitions), including a 5-1 thrashing of Tottenham in the FA Cup semifinals last weekend.

They have taken 11 of a possible 18 points in their last six league appearances, the only real blight a 2-1 loss to Manchester City.

Arsenal are no strangers to putting up five goals on Spurs (see: February 26, 2012), but with their last appearance at the Emirates (a shock 2-1 defeat to Wigan Athletic) looking far more like the Gunners side that went down 2-0 to Tottenham in the first half hour than the one that waxed their rivals 5-0 over the final hour, Chelsea may just fancy themselves here.

Just three days removed from such a massive and emotionally taxing performance (they watched Barcelona hit the post in the 92nd minute), there may be fears that Chelsea will experience a letdown.

But given recent examples, that doesn't seem likely—even without a healthy Drogba.

Di Matteo has said he will rest certain key starters after the Barcelona match, but given the quality available on the Chelsea bench, Arsenal have every reason to still be worried.

Ashley Cole, who ran Djourou ragged in the first encounter with his well-timed runs into the final third, will be a worry for Arsenal.

The Englishman has an exceptional capacity to read the action and get forward at opportune times, but with Bacary Sagna back for Arsenal, his forays should be tempered somewhat.

Chelsea are still seven points removed from third-place Arsenal, albeit with a game in hand—and if that turns into a victory on Saturday, these last three games could get quite interesting.

From an Arsenal perspective, finding themselves in third place after the horror show at the start of the season is cause for celebration in and of itself.

Robin van Persie is still bagging goals—albeit not at the pace he was enjoying in October, where he seemed to score a brace every week—but the most noteworthy change from the side that traveled to the Bridge is in defense.

Gone are Johan Djourou and Per Mertesacker—Arsenal's who both started in defense on Oct. 29, at right-back and center-back respectively—replaced by the first-choice spine of Laurent Koscielny (back from serving a two-match domestic ban) and Thomas Vermaelen.

Bacary Sagna resumes his role on the right, taking over from Djourou, who is, shall we say, less than convincing when he deputizes in that position.

Andre Santos will once again play on the left with Kieran Gibbs ruled out with injury, but the most captivating plot line comes in midfield.

Abou Diaby missed the entire first part of the season due to the latest in a long line of debilitating injuries, but he has returned ahead of Saturday and, with first-choice holding midfielder Mikel Arteta set to miss the rest of the season with an ankle problem, Diaby looks likely to assume that position alongside Alex Song.

The languid Frenchman is a menace when fit, able to keep possession amidst the most furious pressing schemes, and savvy in his distribution. That's the French international side of him.

The downside, which comes all too frequently, is that Diaby is prone to both lapses in concentration and temperament.

Arsenal fans will remember Diaby's sending off against Newcastle United last season, which paved the way for an unfathomable comeback by Toon, who erased a four goal deficit and fought to a 4-4 draw.

No lapses of that sort (or the kind that led to Diaby heading into his own net against Manchester United at Old Trafford back in August, 2009) will be acceptable on Saturday, in a match that Arsenal would do well to win, if only to give themselves from breathing room in third.

Looking to the wings, where Yossi Benayoun is ineligible (he was sent on loan to Arsenal from Chelsea back in August), either Gervinho or Alex Oxlade-Chamberlain look likely to get the nod opposite Theo Walcott on the right.

Benayoun has been Wenger's first choice at the left wing in recent matches, but Gervinho was in fine form against Chelsea back in October, setting up Robin van Persie's first goal with a deft intrusion into the Chelsea penalty area.

The Ivorian, who has been far from his best since returning from the African Cup of Nations in February, is saying all the right things ahead of the match. A good performance from either him or the Ox would be vital.

Tottenham and Newcastle both promise to continue their charge, and Chelsea are a team reborn.

The Blues promise to showcase a far more compact and potent defensive unit than the one in October, a formation that has given Arsenal problems in the past.

Arsenal, coming off a loss in their most recent league match, cannot afford another.

Whatever way you look at it, Saturday promises to be a very interesting match.