Frank Lampard already knows how to get the better of Jose Mourinho as a manager. Just two months into his first coaching job at Derby County last season, Lampard sent his old mentor crashing out of the Carabao Cup with a third-round, penalty shootout victory over Manchester United at Old Trafford. It was a result that made the football world sit up and take notice of Lampard's early steps in management at Derby, and one that also shed light on the losing battle that Mourinho was fighting in his attempt to succeed at United.

Within three months, Mourinho had been sacked at Old Trafford, but Lampard's star continued to rise. After narrowly failing to get Derby promoted to the Premier League, he was handed the challenge of managing Chelsea, the club where he earned legendary status as a player thanks largely to his feats during two title-winning spells under Mourinho. This history lesson is valid because the two men meet again on Sunday, when Lampard's Chelsea travel to Mourinho's Tottenham, but their roles have been reversed: Lampard is suddenly struggling while Mourinho is rediscovering his mojo.

It was a year ago this week that Mourinho lost his job as United manager, with his reputation taking a battering -- in many ways, justifiably -- as a result of the situation he had left behind at Old Trafford. His style of football had become negative, cautious and predictable, his players had grown tired of his repeated public criticism and, most importantly, United's results simply weren't good enough. But just a month into his reign as Spurs manager, the Mourinho swagger is back. Five wins from seven games have helped revive a Tottenham team that had, like his United team last year, lost its way under Mauricio Pochettino.

Mourinho is getting results, making players better -- Dele Alli in particular has been transformed -- and he is once again looking like a manager with a future, rather than one whose best days were behind him. Equally, he will relish the opportunity to take Lampard on this weekend.

Despite a run of four defeats in seven games, his former player has exceeded expectations at Chelsea by steering them into the top four and the knockout stages of the Champions League. But when Mourinho walked into Spurs on Nov. 20, his team was 14th, 11 spots and 12 points adrift of Lampard's Chelsea. When they meet on Sunday, however, a Spurs victory will lift them above Chelsea and complete a dramatic swing of the pendulum in the space of just 33 days. Having been hunted down and beaten by Lampard at Old Trafford last season, Mourinho is now in the position of being able to strike back and show his former player, former club and anybody else he feels needs to see it that there's still plenty of life left in him as an elite manager.

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Sunday's game is such a big one for both Lampard and Mourinho. On a personal level it's a fixture that both will be desperate to win, but it's now a crucial game in the fight for Champions League qualification.

Spurs were almost out of the running when Mourinho walked into the club, but their revival and Chelsea's loss of form has put them back in the frame. Meanwhile, if Chelsea lose and drop out of the top four, it will be the first major setback of Lampard's spell as manager at Stamford Bridge, but it would be compounded by the fact that the blow had been inflicted by Mourinho and Spurs. If Lampard has inspired Chelsea to over-perform with a group of young players and a squad he couldn't strengthen in the summer because of a transfer ban, he's now in the difficult position of having to sustain what many had believed to have been beyond Chelsea this season.

Psychologically, the difference between success and failure this weekend is huge for Lampard and Mourinho. If Lampard wins or avoids defeat, he will have shown the ability to steady the ship and frustrate Mourinho once again. But a Mourinho win would doubtless be exploited to the maximum by the Spurs manager as him getting one over on Chelsea and also putting the young pretender in his place.

The race for fourth place is likely to be a congested one, with United and Wolves also capitalising on Chelsea's recent slump in form to put themselves within reach of the Champions League spots. But right now, Chelsea and Spurs appear to be preparing for a direct battle for fourth. What happens this weekend, between the teams and the managers, could define the rest of the season.