Tottenham versus Chelsea on Sunday means more than just three points in the fight to finish in the Premier League's top four, with what happens in the dugouts likely to be as intriguing as what unfolds on the field.
Spurs go into the game fifth in the standings but just three points behind their London rivals and with a superior goal difference, meaning Jose Mourinho's men can move into the Champions League places with a win over one of his former clubs, who are now managed by a Blues legend he helped turn into a world-class player.
The Portuguese has his own prominent place in Chelsea's history, having led the club to three titles during two separate stints at Stamford Bridge.
For Mourinho, the emotional bond with his players was key to taking them to the next level.
In his autobiography, 'Totally Frank', Lampard revealed that Mourinho told him he was "the best player in the world" during their first pre-season together, in 2004.
A year later, Lampard finished as runner-up to Ronaldinho in the Ballon d'Or rankings, thanks in no small part to the role he played in helping Chelsea end their 50-year wait for a Premier League title with 13 goals, including a double in the decisive win at Bolton.
Lampard never looked back. The belief that Mourinho instilled in him was unshakeable and he went on to captain Chelsea to victory over Bayern Munich in the Champions League final in 2012.
Having become a manager, Lampard is now trying to give his young Chelsea players the same kind of confidence in the hope of transforming the likes of Tammy Abraham, Mason Mount and Fikayo Tomori into superstars.
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Much of Lampard's approach centres on man-management, just like Mourinho, though he comes across as more compassionate.
He shares Mourinho's hatred of losing while he also likes to set up to negate opposition strengths in tactically versatile systems.
However, while Lampard acknowledges that he has learned plenty of lessons from the two-time Champions League winner, whenever the topic comes up, he always insists that he is own man.
“I try to be myself; I think that’s very important,” Lampard told Goal in March.
“Copying anyone as a manager is a mistake. You have to find your own methods or your own ways. I certainly have no fear of tapping into a bit of the managers that I have worked with over the years, but I don’t think I'm similar to any of them.
“I try to take positive points from a lot of people I worked with. In terms of how I work, you have to be reactionary in games, but I try to take things in throughout the week and get all the information to be as prepared as I can be and thorough with the staff that I've got.
“Then, make decisions having done that work, which I think gives you the best opportunity to have success.”
Mourinho, though, continues to have a strong bond with those he managed at Chelsea. Lampard has certainly never forgotten the fact that even after Mourinho had left for Inter, the coach called him regularly after the death of his mother Patricia in 2008.
Mourinho also called to congratulate Lampard on the birth of his daughter just months after Derby had knocked his Manchester United side out of the Carabao Cup in their first meeting as managers.
The pair have had their ups and downs, though. Indeed, it was Mourinho who, in 2014, told Lampard his playing days at Stamford Bridge were over, with Chelsea refusing to extend his contract for another year.It was not the ending to his Blues career that Lampard felt he deserved and he lined up a move to New York City FC, who then opted to loan him to their City Football Group partners Manchester City – and he famously went on to score against Chelsea.
It felt like a semblance of revenge, particularly as it was Mourinho who had said of Lampard's move to the Etihad: "When he decided to go to a direct competitor, then love stories are over.”
Ironically, Mourinho would sign for two further rivals down the line, in United and Tottenham, which has tainted his relationship with Chelsea's fans.
Lampard wasn't happy either with Mourinho's take on Chelsea's 4-0 loss to United at Old Trafford on the opening day of the season. In his role as a pundit on Sky Sports, Mourinho had deemed the Blues "too soft" and criticised Mount for his debut display.
“He didn’t like the performance of Mason Mount? Is that what he said? Did he?" asked an incredulous Lampard. "Wow!
"Well, I can’t drag players out of the medical room to play, so these are the players that played in a game in which we were clearly the better team for 45 to 60 minutes."
And therein lies another similarity between the two: Lampard carries some of Mourinho's famed feistiness when it comes to protecting his players, and his cheeky sense of humour.
Lampard joked that he was happy Mourinho was off Sky Sports when he took the Spurs job a month ago and that came after assistant first-team coach Jody Morris took to Twitter to issue laughing emojis at yet more of his punditry.
Chelsea have since moved warn to him over his social media conduct, with Morris a key figure representing the new era, and the next test of Lampard's bond with Mourinho will be played out in north London in front of TV cameras and 62,000 fans.
The pair are competitors who are trying to balance their past affection with their current burning ambition for victory in one of English football's fiercest derby matches. Their touchline battle will make for compulsive viewing.