Spurs clinched the fourth and final EFL Cup semi-final spot with a dramatic 4-3 win over Manchester United on Thursday night, as the North London side edged out the Red Devils at the Tottenham Hotspur Stadium.
Arsenal will face Newcastle in the other semi-final.
The semi-finals will be played over two legs across the week of January 6th and the week commencing February 3rd.
The winners will battle it out at Wembley Stadium in the final on March 16th.
Tottenham side were cruising at 3-0 in the 54th minute after two goals from Dominic Solanke and one from Dejan Kulusevski.
But Forster's mistakes allowed substitutes Joshua Zirkzee and Amad Diallo to pull the score back to 3-2 with 20 minutes to go.
It was one-way traffic after that, with United totally on top, but Spurs scored a late fourth as Son Heung-min found the net from a corner and they held on despite a late Jonny Evans goal.
Liverpool moved into the League Cup semi-finals as the holders won 2-1 against managerless Southampton, while Gabriel Jesus ended his goal drought with a hat-trick in Arsenal's 3-2 victory over Crystal Palace on Wednesday.
Slot, who watched the quarter-final from the stands while he served a touchline suspension, opted to rest Mohamed Salah and Virgil van Dijk as the Premier League leaders made eight changes.
Liverpool's understudies were too strong for Southampton and Nunez ended his poor recent form with a clinical finish after Jan Bednarek made a hash of clearing Trent Alexander-Arnold's pass in the 24th minute.
At the Emirates Stadium, Brazilian striker Jesus finally found the back of the net on home turf for the first time in 2024.
Jesus' only previous goal in 20 appearances in all competitions this season had come against second-tier Preston in the League Cup.
The Gunners, who last won the League Cup in 1993, are six points behind Liverpool and Mikel Arteta made eight changes as he prioritised Arsenal's rematch with Palace in the top flight on Saturday.
Sandro Tonali scored twice as Newcastle beat Brentford 3-1 at St James' Park.
Magpies boss Eddie Howe named a full-strength side and was rewarded with a comprehensive victory that moved his club a step closer to emulating their run to the 2023 final.
Newcastle, who have not won a major trophy since the 1969 Inter-Cities Fairs Cup, took the lead through Tonali's fine finish from the edge of the area in the ninth minute.