After finishing in fifth place in the Premier League last season, the Lilywhites are set to return to Europe this term after missing out on the previous campaign.
Ange Postecoglou's side have made a mixed start to the new league season, splitting their first three matches with one win, one draw and one loss, leaving them in 10th place heading into the international break.
Spurs' Europa League campaign will get underway on September 26 against Qarabag FK, but there were two notable absentees in the squad list the club submitted to UEFA earlier this week.
Spurs leave out Spence and Reguilon for Europa League campaign
While clubs participating in the Europa League are allowed to submit a 25-man player list for the upcoming Europa League, the Lilywhites could only register 23 players due to a shortage of club-trained options.
As a result, Spurs have chosen to omit former Elland Road loanee Djed Spence and Spanish defender Sergio Reguilon for the first half of the Europa League season, according to transfer expert Fabrizio Romano.
Spence's loan spell at Leeds was prematurely ended last season, as Daniel Farke opted to rely on Archie Gray and Sam Byram for starting duties at right-back.
The 24-year-old could still be added to the squad if Spurs advance past the group stage but the decision to leave Spence out suggests that he may not be too high up on Postecoglou's pecking order, despite making a return this summer.
Reguilon's omission, on the other hand, comes as no surprise, as the Spaniard is widely considered surplus to requirements and could still depart Tottenham Hotspur Stadium, with the Turkish transfer window still open.
Archie Gray to feature in Europe
Meanwhile, Gray has been included in the 23-man squad and is expected to play a significant role in European competition this season, given the demanding schedule Spurs will face and the reduced full-back options now available to Postecoglou.
The 18-year-old was an unused substitute in Spurs' 2-1 loss to Newcastle United at St James' Park last weekend and is currently on international duty with England Under-21s.
Gray has made substitute appearances in Premier League matches against Leicester City and Everton but is expected to play a more prominent role during international duty and in Spurs' upcoming Europa League fixtures.
Under the new format, Spurs are set to face Roma, AZ Alkmaar, Qarabag and Elfsborg at home and Rangers, Ferencvaros, Galatasaray and Hoffenheim on the road.