For the past two-and-a-half seasons Marcelo Bielsa has kept changes to his Leeds United starting XI to a minimum.
The Whites head coach likes to run with a small first-team squad and does not generally tinker with his line-up unless his hand is forced, as he keeps the faith with his core group of players.
That can mean opportunities can be limited for those on the fringe of the starting XI, often leaving cup competitions as a vital source of first-team minutes.
Leeds' humbling 3-0 defeat at Crawley Town saw Bielsa make seven changes from the club's last outing in the Premier League and it is clear that many of them failed to take advantage of the chance they were given.
Questions have therefore been asked of Leeds' strength in depth in the wake of the defeat to the League Two side, amid worries that any potential injuries in key positions could cause the side real issues.
Here is a look at the options Bielsa has in each position.
Goalkeepers
Illan Meslier, Kiko Casilla, Elia Caprile
Illan Meslier's excellent early Premier League form quickly settled any lingering debate about who Leeds' number one should be, but the worry here is whether or not Kiko Casilla is an able deputy.
The evidence on show at the Broadfield Stadium suggests not, with the former Real Madrid man's error for the second goal a reminder of the numerous mistakes he made last season before he was sidelined for eight-match after his suspension. A hefty contract means Leeds may to stick with the Spaniard for at least the immediate future,.
Behind him is 2020 January window signing Elia Caprile, who has shown promise in the under-23s but would be a very inexperienced option in the Premier League.
Centre-backs
Liam Cooper, Robin Koch, Diego Llorente, Pascal Struijk, Luke Ayling, Kalvin Phillips, Leif Davis, Oliver Casey, Charlie Cresswell, Gaetano Berardi
Leeds invested heavily at the back in the summer window, bringing in German and Spanish internationals in the shape of Robin Koch and Diego Llorente. Both are currently sidelined through injury, with skipper Liam Cooper having just returned from a spell out, meaning depth has been tested here in recent weeks.
Pascal Struijk and Luke Ayling forged a useful partnership at the back, meaning that Bielsa has five genuine options here before he had to move too many players out of position or call on untested youngsters.
Right-back
Luke Ayling, Stuart Dallas, Jamie Shackleton, Gaetano Berardi, Cody Drameh
The form of ever-reliable duo Luke Ayling and Stuart Dallas means Leeds have not had any problems in this area this term. Jamie Shackelton's energy makes his a good third-choice option, while Bielsa has suggested that Gaetano Berardi may be an option again as soon as February following his long-term injury. Cody Drameh has been excellent for the under-23s this term and looks to have all the attributes that Bielsa looks for in a full-back.
Left-back
Stuart Dallas, Gjanni Alioski, Leif Davis, Pascal Struijk
A common problem position at Elland Road in recent times. While not a natural left-back, Dallas has made the position his own over the past 18 months, with Gjanni Alioski a dependable option. Leif Davis is one of the club's best youngsters, but you do get the feeling Leeds are lacking a specialist, Premier League quality left-back in their current squad.
Defensive midfield
Kalvin Phillips, Pascal Struijk, Robin Koch, Diego Llorente, Jamie Shackleton, Jack Jenkins, Adam Forshaw
A hugely important part of Bielsa's set-up and a position that Kalvin Phillips has made his own. Struijk has moved up the pecking order as the England international's main deputy this term, while Koch and Llorente have both operated in this position in the past. Jack Jenkins is the new kid on the block here, having made his debut at Crawley following several appearances on the first-team bench.
Central midfield
Mateusz Klich, Stuart Dallas, Rodrigo, Jamie Shackleton, Jack Jenkins, Sam Greenwood, Adam Forshaw
Another position with a undisputed starter in the ever-dependable Mateusz Klich. Only once in 112 matches has the Pole not been named in a Bielsa league starting XI, so we have limited evidence of anyone else operating in the number eight role. Dallas is an option here, as he is in most positions, as is Jamie Shackleton. Rodrigo also has the skillset to play here, while in the academy Jenkins has played there, as has Sam Greenwood in recent weeks.
Attacking midfield
Rodrigo, Pablo Hernandez, Raphinha, Mateusz Klich, Tyler Roberts, Jack Harrison, Ian Poveda, Sam Greenwood
Record signing Rodrigo has made the number ten role his in recent weeks, taking the mantle from his compatriot Pablo Hernandez, who has seen his role reduced this season. Klich also relishes any opportunity to operate near the opposition goal, while Leeds' attacking options here are supplemented by their many wide players.
Right-wing
Raphinha, Helder Costa, Ian Poveda, Jack Harrison, Pablo Hernandez, Tyler Roberts, Stuart Dallas, Rodrigo
The deadline day £17million deal that brought Raphinha to Elland Road looks better and better by the week, with the Brazilian relegating Helder Costa to a back-up on the right. Ian Poveda has a habit of making the most out of his substitute appearances and will be looking to move ahead of the Portuguese in the pecking order this season.
Left-wing
Jack Harrison, Gjanni Alioski, Raphinha, Helder Costa, Ian Poveda, Tyler Roberts, Stuart Dallas
Jack Harrison is another near-constant under Bielsa, with Gjanni Alioski another out-and-out left-sided option. After that the rest of Leeds' widemen can also fill in on the left.
Striker
Patrick Bamford, Rodrigo, Tyler Roberts, Jack Harrison, Sam Greenwood, Joe Gelhardt
Another position with a clear incumbent. Patrick Bamford's absence at Crawley showed just how key his skillset is for Bielsa's system, with Rodrigo unable to be the kind of outlet that the Leeds number nine has been this season. Tyler Roberts has not made much of an impact since Leeds were promoted back to the Premier League and after the Welshman it's a case of square pegs in round hole (Harrison) or untested under-23s in Greenwood and Joe Gelhardt.
