Tottenham's lack of options to Harry Kane remains an issue for Pochettino
Last summer, Mauricio Pochettino stressed the need to put pressure on his top players and ensure they did not become too comfortable.
Progress has been made. Tottenham look less reliant on Toby Alderweireld than last season, and there is strong competition in the full-back spots and central midfield -- or there will be when everyone is fully fit.
Pochettino has more selection headaches further forward, too, and Dele Alli will need to perform to keep his place -- Son Heung-Min, Erik Lamela and January signing Lucas Moura have all scored more recently.
Yet there is still work to be done, and Christian Eriksen and Harry Kane remain untouchable. Particularly Kane.
Nowhere else in the squad is the gap between the first-choice and reserve player so large and, unlike in other areas, the problem is only getting harder to solve. A new signing will not necessarily tick the box.
Spurs opted for a youthful understudy, Vincent Janssen, in 2016, before replacing him with the experienced Fernando Llorente last summer.
The problem has been the same. Neither player has had enough game time to establish a rhythm or gain the confidence needed to adequately deputise for Kane, let alone challenge him.
For his own part, Tottenham's hitman has been utterly ruthless in keeping the door firmly locked, refusing to give Pochettino any reason to look elsewhere for goals. He has scored in eight of his past nine games.
On top of his natural professionalism, Kane is relentlessly chasing records -- a third successive Golden Boot, Jimmy Greaves' all-time goal-scoring record for Tottenham, Alan Shearer's spot at the top of the Premier League's scoring chart, which is often underestimated as a reason he might stay at Tottenham.
Aside from the fact it is his boyhood club, and he is playing for them in the most exciting period of their recent history, he knows he will start almost every match and will be given every chance to write his name into history.
There is little evidence that he needs competition within Spurs' squad, or extra motivation, to maintain his incredible consistency.
Yet Tottenham still need an insurance policy for when he is injured, and it is proving impossible to find someone who can shake off the rust whenever required and replicate Kane's impact -- even for a man with Llorente's CV.
To make matters worse, Kane is only improving and adding to his skillset.
Llorente was supposed to provide an alternative to Spurs' star striker, offering more physicality, an aerial threat and a Plan B -- yet Kane has looked more effective in each of those areas. It is almost as if he took Llorente's arrival as a challenge.
Kane's hold-up play has noticeably improved this season, and he has developed a real knack for getting his body in front of defenders to win free kicks.
He is frequently coming out on top in the physical battles against centre-backs and, when it comes to his aerial ability, his decisive header against Arsenal said it all. Meanwhile, Llorente missed a sitter against Newport County.
Kane has become such a complete forward that it is tough for anyone else to offer different talents and complement him, so it has not even proved particularly fruitful to give Llorente time alongside him.
Playing the forwards together worked to an extent against Real Madrid at the Bernabeu, and away against Apoel Nicosia as Kane arrived late in the box to score twice soon after his partner's introduction.
But, when Spurs hosted AFC Wimbledon last month, Llorente seemed to get in Kane's way, and the England forward netted twice shortly after the Spaniard's withdrawal. Similarly, away against Newport, Spurs improved after Llorente went off and it was then that Kane equalised.
The upshot is Llorente was not even named on the bench against Arsenal and Juventus this month.
There seems every chance the 32-year-old will go the same way as Janssen, through the exit door, so what then? Do Spurs look elsewhere again, or does Janssen step back into his old role when he returns from his loan at Fenerbahce in the summer? Would he want to?
Perhaps Llorente's omission from recent squads hints at an alternative strategy.
Given their wealth of exciting attacking midfielders, could Tottenham go into next season without a Janssen or Llorente, trusting Son or Alli to lead the line if necessary? Would that be too great a risk?
Might the club look for a flexible attacking player who can play out wide or through the middle? Or do they have enough of those?
These are interesting questions because, since Spurs' strength in depth has improved in other areas, players must now look capable of making an impact and improving the team's performance just to earn a spot among the substitutes.
It has become increasingly difficult for Spurs' second-choice strikers to provide that assurance, to the extent that Pochettino has recently decided Llorente would be wasting valuable space on the bench.
As a result, while Kane's teammates are now fighting harder than ever for their places, he has never looked so secure.
Ben is ESPN FC's Tottenham blogger. Follow on Twitter: @BenPearceSpurs.