Just four points now separate the two sides in the table and Spurs could deal another blow to Chelsea's campaign by reaching the final for the first time since 1991.
For the vast majority of the season it has looked as though Antonio Conte's first campaign in English football would end with at least one piece of silverware.
The Blues' imperious form in the Premier League also made them favourites to go all the way in the FA Cup, but in recent weeks the previously unflappable West Londoners have begun to waver.
Chelsea began the month of April with a 10-point gap over Spurs at the top of the Premier League table, but defeats to Crystal Palace and Manchester United have seen that lead cut to four points with six games of the season still remaining.
It could be the case, then, that Spurs are responsible for ending Chelsea's hopes on both fronts, although Conte will be reminding his side that they still have the upper hand despite the form book being in Tottenham's favour.
Chelsea have not lost back-to-back matches for more than a year, but defeat to Spurs could have an even more damaging effect than seeing them crash out of the FA Cup and would certainly ramp up the pressure ahead of tricky fixtures against Southampton and Everton in the league next week.
However, when it comes to stages like Saturday's Chelsea have the edge in terms of experience - the Blues have won the FA Cup six times since Spurs last lifted the trophy, most recently doing so in 2012.
Conte's side have made no mistake on their way to the semi-finals either, cruising past Peterborough United, Brentford and Wolverhampton Wanderers before a 1-0 triumph over 10-man Manchester United sealed their place in the final four.
United got revenge for that loss with a 2-0 win on Sunday, and Conte will want a response from his side after seeing them fail to even register a shot on target at Old Trafford - the first time that has happened to Chelsea in the league for more than a decade.
The coming weeks are sure to test Chelsea's mettle, but if they are to continue their quest for an eighth FA Cup crown beyond this weekend then they will need their full focus on Wembley and a Tottenham team full of confidence.
Recent form: WWWW
Recent form (all competitions): WWLWWL
Tottenham's progress under Mauricio Pochettino has been clear to see, but a tangible reward has so far eluded the Argentine since he arrived at the club.
There are plenty of reasons for optimism - a young team bursting with potential have established themselves as the closest challengers for the title in each of the past two seasons in addition to sealing a return to the Champions League.
However, there is nothing quite like a trophy to truly mark progress and, while Tottenham's hopes in the league look significantly better now than they did at the start of the month, the FA Cup remains their best chance of picking up silverware this season.
It is a trophy that Spurs have not won for 26 years - too long a drought for a club of their calibre. Only Arsenal and Manchester United have won the competition on more occasions than Tottenham's eight, but the Gunners have lifted the trophy seven times and United have added five more to their tally since Spurs' last triumph.
There are plenty who will make them favourites to finally end that long wait this season, though, as they approach the business end of the competition in scintillating form.
Spurs have won their last eight matches across all competitions and have only been on a better run once in their history - a 13-game streak in 1960. Goals have flown freely in that time too, with Tottenham finding the back of the net 28 times during that spell - including back-to-back 4-0 triumphs in their last two outings.
The last time Spurs failed to win a match was their last game at Wembley, though, and the return to the national stadium will be as much a concern for many fans as the strength of their opposition.
Since beating Chelsea in the 2008 League Cup final Tottenham have won just one of their eight matches at Wembley, drawing two and losing five including two in the Champions League group stages this season.
Pochettino has repeatedly brushed off suggestions of a Wembley hoodoo, but when compared with their White Hart Lane form of 19 wins and two draws from 21 home games this season it is clear that something is amiss when they switch stadiums.
Curse or no curse, it is a problem that Spurs will need to rectify if, as expected, they are to make Wembley their home ground while the new White Hart Lane is being completed next season, and Saturday's match would be the perfect time for them to do that.
Chelsea represent the first Premier League opposition that Spurs have come up against in this season's competition, though, having dispatched of Aston Villa, Wycombe Wanderers, Fulham and Millwall in the previous rounds, scoring 15 goals in the process.
Recent form: WWWW
Recent form (all competitions): WWWWWW
Chelsea could once again be without Thibaut Courtois, who missed Sunday's defeat to Manchester United with an ankle injury sustained while filming an NBA commercial.
Reports have suggested that Victor Moses, Gary Cahill and Diego Costa have also been affected by the bug, but all three are expected to be in the starting XI once again and Conte could name the strongest side available to him.
Spurs are still without Danny Rose, although the full-back has returned to training and could make his comeback from a knee injury in the North London derby next weekend.
Despite his side's recent form, Pochettino could make a tactical switch in order to match up against Chelsea's 3-4-3 system having done so during their 2-0 Premier League win over Chelsea in January.
Chelsea possible starting lineup:
Begovic; Azpilicueta, Luiz, Cahill; Moses, Kante, Matic, Alonso; Pedro, Costa, Hazard
Tottenham possible starting lineup:
Lloris; Dier, Vertonghen, Alderweireld; Walker, Wanyama, Dembele, Davies; Eriksen, Kane, Alli
Head To Head
These two sides have been evenly matched with two wins apiece and two draws over the past six meetings, although looking further back those are Tottenham's only two victories from their last 16 games against Chelsea in all competitions.
This will be their 12th FA Cup meeting, and Chelsea edge the overall record with five wins to Tottenham's four, including a 5-1 drubbing of Spurs when they met in the semi-final five years ago.
Chelsea are unbeaten in their last four FA Cup clashes with Spurs - a run which stretches back to 1982 when Glenn Hoddle was amongst the scorers in a 3-2 quarter-final win at Stamford Bridge.
We say: Chelsea 1-2 Tottenham
This match could go either way. These two sides have been the best in England this season and it promises to be a memorable occasion with plenty of sub-plots, but we're backing Spurs to come away with the victory mainly due to their impeccable recent form. Both teams have players capable of lighting up the big occasion, though, so it could be that this one goes all the way to penalties.