Benitez today revealed that captain Jamaal Lascelles will miss tomorrow evening's match against Manchester United along with Christian Atsu and Mikel Merino.
"Merino's been with a member of staff in Spain," said United's manager.
"He will come back and hopefully start training here. Jamaal and Atsu are injured."
Meanwhile, Paul Dummett, sidelined since the first weekend of the season, is edging closer to a comeback from his hamstring problem.
Sea fret - a look at the foggy phenomenon which spoils sunny days in South Shields
South Shields man jailed for terrifying physical and sexual assault on woman in her own home
Pair set up cannabis farm in town centre flat
South Tyneside man given jail warning after breaching court order
13 great pictures as the sunshine sees crowds flock to South Shields beaches
"Dummett's getting closer," added Benitez. "He's training with us."