Everton's Carlo Ancelotti has never been stood opposite Leeds United's Marcelo Bielsa in the dugout, but the two giants of management will lead their respective teams into battle for the first time this weekend.
Ancelotti is famed for being a shrewd, unmoved, wily character. He is wise, does not engage in theatrics on the touchline or in the media and conducts himself in a very composed manner. The same can be said of Bielsa during his tenure at Leeds, aside from a handful of well-documented eccentricities.
Everton's defensive structure has been the topic of much discussion this season. It has backed up a strong attack which is firing on all cylinders, but truth be told, has leaked too many goals.
In the Toffees' latest outing, they triumphed 3-2 over Fulham at Craven Cottage, but forfeited plenty of opportunities in the second half, as they lost their grasp on the game.
Despite this weekend's fixture taking place at Goodison Park, a stadium Leeds have not visited for over 17 years, Bielsa's side will hope to maintain a firm grip on proceedings throughout the 90 minutes.
Ancelotti's men lined up in a 3-4-3 against the Cottagers last time out, with usual incumbents Yerry Mina and Michael Keane joining Ben Godfrey in central defence. The ex-Norwich City man has been utilised at right-back this season, but has not looked entirely comfortable in that role, hence the change in formation.
Mason Holgate's return to the fold also offers Ancelotti a very good ball-playing presence, capable of supplementing the Blues' defensive structure with his ability to play out. A three-man defence against Leeds would also allow for Everton's best creative weapon of last season - Lucas Digne - to play in a more advanced, left wing-back role. From these positions he would be particularly dangerous, servicing Richarlison and especially Dominic Calvert-Lewin.
That said, if Everton do commit to deploying three central defenders and wing-backs, Leeds will certainly find spaces in behind, particularly in wide areas. We have seen throughout Marcelo Bielsa's tenure how frequently his full-backs like to play long, diagonal passes to the winger on the opposing flank.
Overloads in wide areas, which worked to good effect against Arsenal, could be devastating to an Everton side understaffed in these positions, and subsequently drag the defensive midfielders Allan and Abdoulaye Doucoure out of position to compensate.
Equally, Ancelotti's recent tinkerings could be a ploy to distract and confuse Marcelo Bielsa as to which approach he intends to use. Ancelotti will know full well how much preparation goes into Bielsa's pre-match musings on the opposition, therefore any attempt to muddy the waters could lead to Bielsa's attentiveness being spread more thinly across multiple formations.
In Ancelotti's 33 games with Everton, he has lined up with a back three on just four occasions - three of which have ended in defeat to Manchester City, Liverpool and Wolverhampton Wanderers - according to Transfermarkt. Throughout his most recent stint at Napoli, Ancelotti exclusively played with a back four and at Bayern Munich he rarely used anything other than a 4-3-3, the system he has used most frequently this season.
On the balance of probabilities, Everton will revert back to their four-man defence against Leeds, with Ancelotti probably preferring to trial his rarely-tried systems for lesser tests such as Fulham or West Bromwich Albion.
