And while on-loan Blues player Kenedy's exclusion was logical, the absence of Lascelles raised a few eyebrows when Benitez revealed his starting XI.
Kenedy is barred from facing his parent club for the duration of the loan spell, in line with Premier League regulations on such transfers.
The Brazilian first moved to Tyneside in January 2018, and Newcastle opted to extend his stay for the current season while also sealing a purchase option on the winger.
He featured in both of Newcastle's opening Premier League games before being forced to sit out Sunday's clash.
Lascelles, meanwhile, missed out altogether on a place in Benitez's three-man central defence, with summer signing Federico Fernandez, Fabian Schar and Ciaran Clark preferred.
While neither the club nor the player have spoken as of yet on the absence, reports suggest that Lascelles was ditched after clashing with Benitez at training.
An alleged bust-up concerning tactics, specifically on the implementation of the back three against the Blues, seems to lie at the heart of the conflict between the pair.
Club guidance is Lascelles and Shelvey have knocks. Lascelles (ankle) Shelvey (thigh) #nufc— Lee Ryder (@lee_ryder) 26 de agosto de 2018
The defender apparently wished to play in the middle of the trio, while Benitez insisted on placing him on the right.
Newcastle, however, have publicly asserted that Lascelles' absence owes to an ankle problem.
Lascelles, who has made over 100 appearances for Newcastle, was later pictured in the stands at St. James' Park as the Magpies, shorn of their captain, looked to upset the odds and defeat Maurizio Sarri's charges.