Throughout Jose Mourinho's two spells at Stamford Bridge, Arsenal have always represented welcome opposition for Premier League champions Chelsea.

Indeed, Arsene Wenger's record against the Special One is infamously woeful; seven wins and six draws from 13 competitive fixtures, Le Professeur's only respite coming in the 2015 Community Shield final during the summer.

But these are dire times in west London as the Blues' title defence hangs in the balance after just five games. They've already recorded as many defeats as last season, three, and are currently in 17th place with the worst defensive record in the division - 12 goals conceded and no clean sheets.

Therefore, Saturday's 12.45pm kick-off at Stamford Bridge is unquestionably the Gunners' best chance yet to get one over Mourinho in a competitive fixture. That, however, could well depend on Arsenal dominating the FIVE key individual battles Football Fancast have listed in this article.

Who are you tipping to claim all three points on Saturday? Comment below!

DIEGO COSTA VS PER MERTESACKER

Per Mertesacker's experience, leadership and aerial dominance was sorely missed in midweek as Arsenal conceded twice to a Dynamo Zagreb outfit whose last Champions League victory was all the way back in 1999.

The German international sat out the European fixture with a virus but is expected to return this weekend, fortunately enough just in time to face one of the most formidable front men in the Premier League - Diego Costa.

The Spain international's struggled for form this season - as have most of Chelsea's players - but he scored an absolute stunner against Maccabi Tel Aviv on Wednesday, which could provide the confidence boost he desperately needs.

Whilst Laurent Koscienly sweeps up behind, it will be Mertesacker's job to keep Costa at bay. No easy feat considering the ruthless efficiency the 6 foot 2 striker showed last season, but the German international has the height, power and experience to do so.

MESUT OZIL VS NEMANJA MATIC

This is now Mesut Ozil's third season at Arsenal yet the jury's still out on whether he's proved a worthwhile addition at a club-record cost of £42.2million.

He seemingly revolves between being the best player on the pitch one week and completely anonymous the next. Overall, he's yet to truly prove the deciding factor for the Gunners in an important game - perhaps with the exception of a Man of the Match display against Napoli way back in 2013.

That being said, the World Cup winner's pedigree, intelligence and technical quality is without doubt, so he must be kept on a tight leash at all times.

That duty predominantly falls to Nemanja Matic as Chelsea's deepest lying midfielder, who has struggled to assert his habitual dominance on the middle of the park in the Blues' opening fixtures.

The Serbian international has certainly performed better than some, however, evident enough through his wonder-strike against Everton last weekend, and is still one of the best playbreakers in the Premier League, last term averaging 3.6 tackles and 2 interceptions per match.

To ensure another lukewarm afternoon for the German international, Chelsea need a big performance from their monolithic midfielder.

ALEXIS SANCHEZ VS BRANISLAV IVANOVIC

The Sanchez-Ivanovic appropriated flank could well be where this fixture is lost and won. After all, the Chile international is Arsenal's most dangerous attacking threat, despite being yet to get off the mark this season, whilst Ivanovic has been amongst the biggest culprits behind the woeful start to Chelsea's title defence.

Indeed, the Serbian international has been dribbled past on ten occasions already this year; the most of any Premier League defender and nearly two-thirds of his total from last term in just five appearances. Sanchez, meanwhile, has averaged 2.75 successful take-ons per-match throughout his Premier League career, whilst his firepower - bagging 16 in 35 last term - remains undoubted.

That gives me a sneaking suspicion we might see somebody else take the No.2 mantle against the Gunners. Cesar Azpilicueta could switch back to his favoured right-hand side, making way for midweek debutant Baba Rahman on the left, or Kurt Zouma's pace, power and domineering stature could be put to use instea.

Whoever starts as Chelsea's right-back, however, it's imperative they receive protection from in front and aren't left in too many one-on-one situations. With Pedro and Willian both ruled out of the Stamford Bridge meet through injury, that task could fall to workaholic Ramires or potentially youngster Kenedy.

CESC FABREGAS VS SANTI CAZORLA

These two are by no means a straight-up battle like those aforementioned on this list.

Even if Cesc Fabregas is selected at No.10 - highly possible considering the injury to Willian, Oscar's only recent return to fitness and the lack of defensive protection he's offered alongside Nemanja Matic this season - Arsene Wenger won't expect Santi Cazorla to keep tabs on him. That duty will be predominantly Francis Coquelin's.

Yet, Cazorla and Fabregas both perform similar duties for Arsenal and Chelsea respectively, namely, keeping the midfield ticking over when in possession and providing those incisive passes forward.

Cazorla has certainly enjoyed better form than his countryman this season, averaging a whopping 4.6 created chances per match compared to Fabregas' 1.6 - which is actually lower than Gunners right-back Hector Bellerin.

But the 28 year-old will be determined to put in an improved performance against the club he once captained to silence the criticisms that have continuously accumulated since the turn of 2015.

Likewise, neither are what you'd describe as defensively-minded players, in fact quite the opposite, which is a weakness Arsenal and Chelsea will both look to exploit on Saturday.

EDEN HAZARD VS HECTOR BELLERIN

It's been a troubling start to the season for Eden Hazard, who is yet to get off the mark in the Premier League and uncharacteristically blazed a penalty over the bar against Maccabi Tel Aviv in midweek.

But the Belgium international's quality remains indisputable as last season's PFA Player of the Year and his overall form is by no means as disturbing as his goal tally, averaging 3 successful dribbles, 1.2 shots and 3.4 created chances per match in the Premier League.

Especially following Mathieu Debuchy's tepid showing during the Dynamo Zagreb defeat, he'll likely be up against Arsenal's Hector Bellerin on Saturday - who is by no means the most natural of defenders.

Indeed, the Spaniard loves to bomb forward, evident enough through his 1.8 created chances per match this term, and even when up against the biggest talent in the Premier League will still look to join the attack as much as possible.

Whilst that in theory makes Hazard's job much easier, it also creates a few headaches for the 24 year-old. As much as he'll have his heart set on exploiting the gaps Bellerin inevitably leaves behind, Hazard also needs to ensure the right-back isn't allowed time and space on the overlap. He's not only capable of creating chances but also scoring them, boasting two from 20 outings last season.