Three contrasting lessons from Tottenham's defeat of Arsenal

Mauricio Pochettino needs a midfield link deputy for Dembele
Mousa Dembele has been one of Tottenham's standout performers throughout this season, establishing a superb dynamic alongside Victor Wanyama in Pochettino's engine room.
Whilst Wanyama provides a physically combative shield for defensive duo Toby Alderwerield and Jan Vertonghen, it is Dembele who connects the deeper lying midfield with the creative talents of Christian Eriksen, Dele Alli and Son Heung-Min. Essentially, Dembele is the crucial link that knits the Spurs unit together.

However, when unavailable - as injuries have occurred in recent times - Dembele is hugely missed. Against Arsenal, Pochettino seemed evidently aware of the gap left by Dembele's absence; to such an extent that the Spurs boss switched system in order to facilitate Eric Dier alongside Wanyama - a combination that is simply not as effective.
Whether the talented Harry Winks can be earmarked to deputise for Dembele remains to be seen - but what is clear is that the Belgium international is close to being invaluable and irreplaceable at White Hart Lane.

Eric Dier's best position
Whether England international Eric Dier is deployed in midfield or defence, there inevitably exists a sense of reliability and trustworthiness surrounding the 23-year-old. However, as Spurs look to launch a serious title winning challenge in the upcoming years, it is vital that Dier establishes himself as a clearly identified role - for both his club and country future.
Dier, whilst efficient, tends to appear slightly limited whenever fielded alongside Wanyama - perhaps in part to the similar traits that both players possess - and is by no-way a like-for-like replacement for Dembele.
However, the utility man certainly supplements Alderweireld and Vertonghen as part of a back three - where his ability to step into midfield areas and distribute is just as effective as the Belgium international centre backs.

Son Heung-Min can supersede Christian Eriksen
Alongside Dele Alli, Spurs possess another outstanding offensively minded talent in the guise of Christian Eriksen. Since signing from Ajax, Denmark international Eriksen has evolved into a true Premier League standout - with recent transfer links to Barcelona indicative of Eriksen's ability and progress at White Hart Lane.
Any potential Eriksen departure - however unlikely - would be a blow to Pochettino's title aspirations; but there may well be a ready-made heir to Eriksen's midfield throne within the current Spurs squad.

South Korean star Son Heung-Min has emerged as marvellous member of Tottenham's line-up this season. Following a £22m transfer from Bayer Leverkusen in the summer of 2015, Son has taken his time to fully adapt and impact on the Premier League. However, with 12 goals and almost as many assists from his 29 appearances this term, Son is becoming a significantly important contributor.
With a superb ability to carry the ball into threatening areas, combined with admirable distribution, Son certainly has the attributes to supersede Eriksen - should the time ever arise.