Last season's runners-up play a few hours before their title rivals, who face a far tougher assignment away at neighbours Atletico Madrid in what could be a pivotal weekend in the Spanish top flight.
The four-point margin on the bottom three last time out now stands at a healthier 11 points this time around, but recent results suggest that Los Legionarios - more accustomed to playing football in the lower leagues since being formed 89 years ago - are on the slide.
Back-to-back defeats heading into the the international break, going down 2-1 to Sevilla and 3-0 to Valencia away from home, have blighted what was otherwise a fine start to the 2017-18 campaign for Garitano's charges.
Prior to that, Leganes had won three and drawn two of their previous five league outings in a run that includes a goalless draw against Atletico Madrid here in late September.
Their overall home form is pretty mixed, however, having won two, drawn two and lost one, but Leganes certainly know how to make life tough for the opposition - regardless of their calibre.
Only two of the last eight sides to visit this compact venue have managed to find a way through, giving the Madrid-based side the third-best defensive record overall so far this season.
Indeed, only Barcelona and Atletico have conceded fewer at home and away, though it is at the other end of the pitch where improvements can perhaps be made as just nine goals have been scored.
Keeping things tight will be the gameplan adopted by Garitano on Saturday afternoon, as he aims to strangle out Barca's attacking talents in much the same way as he achieved when Atletico visited here seven weeks ago.
Recent form in La Liga: WDWWLL
Recent form (all competitions): WWWWLL
For all the talk of a Camp Nou crisis a week or so into the season, Ernesto Valverde deserves huge praise for not only steadying the ship but also making his side more of a force than they were in Luis Enrique's final season at the helm.
The performances have not always been full-throttle, having scraped narrow wins against Getafe and Sevilla of late, but Barca now have a knack of getting the job done.
Only once in the last six seasons have they started a campaign as well as this, having won 10 of their 11 La Liga matches to move four points clear of surprise challengers Valencia and, perhaps more importantly at this stage, eight in front of Real Madrid.
If the 5-1 Supercopa de Espana defeat to Los Blancos was their nadir, coming at a time when one of their star players had just departed and moves for a number of potential replacements fell flat, then snatching the La Liga title - and indeed Champions League crown - back from Madrid will be the greatest of achievements for Valverde.
Even the recent goalless draw away to Olympiacos has done little to halt the Catalan giants' momentum, as they returned to winning ways against Sevilla a fortnight ago to make it 14 victories from 16 games overall in Valverde's first campaign at the Camp Nou helm.
Barcelona's tally of 30 goals scored is the joint-best in the division, with Lionel Messi responsible for 12 of those, while just four goals conceded cannot be matched by any other side - Valverde appears to have found the perfect balance, even if star man Luis Suarez has badly faded this term.
With a place in the last 16 of the Champions League effectively sealed ahead of next week's trip to Juventus, and a 3-0 lead built up ahead of their Copa del Rey second leg against Murcia, Barca can now focus on extending their advantage over Real Madrid.
The two sides are due to face off in the Spanish capital in the final round of matches prior to the winter break but, on the basis of the first three months, Barca may already have one hand on the top-flight crown by then - not many would have predicted that outcome the last time the two sides faced off.
Recent form in La Liga: WWDWWW
Recent form (all competitions): WWWWDW
Leganes possible starting lineup:
Cuellar; Zaldua, Siovas, Munoz, Rico; Eraso, Perez, Pires; Amrabat, Beauvue, Szymanowski
Barcelona possible starting lineup:
Ter Stegen; Semedo, Pique, Umtiti, Alba; Alcacer, Rakitic, Busquets, Iniesta; Suarez, Messi
Head To Head
These two sides have met on a couple of previous occasions, with Barcelona twice coming out on top in last season's La Liga clashes.
More recently, a last-gasp Messi penalty rescued a lacklustre Barcelona as they carved out a 2-1 win against the newly-promoted side in Catalonia eight months ago.
We say: Leganes 0-2 Barcelona
Leganes do not tend to concede many goals on home soil, but they come up against the division's most potent attack on Saturday afternoon. Catching the league leaders cold is their best bet, with a number of players only just returning from international duty, though collecting a point or more from this fixture will be seen as a huge bonus for Garitano.