Aitor Karanka says Boro will check on the fitness of three players ahead of Boro's trip to the south coast on Sunday.
Alvaro Negredo, Gaston Ramirez and Jordan Rhodes are all doubts, while George Friend will also miss the weekend's fixture.
"Alvaro, Gaston and Jordan couldn't train with the team today," Karanka said.
"I need to check tomorrow with the doctors.
"The main thing for me is the players who are ready to play are ready to take that chance."
Meanwhile, Karanka is pleased with George Friend's recovery process so far.
"George it taking steps, and hopefully tomorrow he will train with us, as it's not a hard session," he said.
"Hopefully he can be with the team on Monday.
"I think from his injury point of view he is ready but maybe not his fitness, knowing George is a fit lad."