While Carlisle have made a slow start to the new season and parted ways with their manager at the weekend, Forest's youngsters will arrive at Brunton Park in much better form.
Match preview
Local hero Paul Simpson has again left Carlisle United following Saturday's 2-1 home defeat by Tranmere Rovers, as his second spell in charge ended with the club sitting 20th in the early League Two table.
Carlisle-born Simpson - who also finished his playing career at Brunton Park - returned as manager in 2022, leading the Blues to promotion.
However, they were relegated to England's fourth tier last season following a dismal run of nine defeats from 10, and they have now lost three of four league matches this term.
Other than a gritty win over Barrow, the Blues have not been able to convert chances into points, and change became almost inevitable.
The Cumbrian club's Florida-based ownership have now decided to act, so a caretaker team will be in charge for Carlisle's cup clash in midweek.
By contrast with their hosts, Nottingham Forest Under-21s are flying high in Premier League 2 this season, having posted three wins from three to start the campaign.
Following an opening-day defeat of Wolverhampton Wanderers, Forest's young guns beat Norwich City 3-0 and then Reading 2-0.
As a result, Warren Joyce's side have claimed maximum points without conceding a single goal so far, putting them joint-top of the table with Arsenal and West Ham United.
Now, in a group also featuring Morecambe and Wigan Athletic, the top-flight club's Under-21 team can test themselves against senior professionals in the EFL Trophy.
Carlisle United form (all competitions):
W
L
L
W
L
L
Nottingham Forest Under-21s form (all competitions):
Team News
Under temporary management, and with an important league game against Bradford City scheduled for the weekend, Carlisle are likely to make changes to the side that lined up against Tranmere.
Dylan McGeouch and Cameron Harper could be involved after returning from injury, while Ben Barclay and Sam Lavelle may be back in the starting XI.
Captain Charlie Wyke should feature up front, possibly supported by Jordan Jones, who made his debut in the Blues' weekend defeat.
Meanwhile, Nottingham Forest Under-21s will name their strongest possible side on Tuesday, including 18-year-old winger Jimmy Sinclair, who has scored twice this season in Premier League 2.
Left-back Josh Powell was also on target last time out, and he should start in the visitors' back four.
Carlisle United possible starting lineup:
Breeze; Davies, Hayden, Lavelle, Mellish, Williams; Jones, Barclay, Neal; Armstrong, Wyke
Nottingham Forest Under-21s possible starting lineup:
Bott; Back, Hammond, McAdam, Powell; Perry, Perkins; Sinclair, Nadin, Newton; Gardner