Sunderland have been linked with a six-month loan move for former Liverpool midfielder Joao Teixeira in January.
The 23-year-old is yet to make an appearance for Portugese giants Porto after signing for the club in the summer after his release from Liverpool.
Teixeira failed to make an impact on Merseyside and was loaned out to Brentford and Brighton during his three-year spell in the North West.
For the latest Sunderland AFC transfer news click here:
Manager David Moyes is desperate to see the efforts of Jermain Defoe get rewarded with points rather than just platitudes.
The striker has been largely starved of possession as Sunderland have struggled in the opening weeks of the season.
Defoe scored twice against Crystal Palace to put Sunderland 2-0 up but a late collapse saw the Eagles leave with all three points.
"Jermain did what he had to do," said Moyes.
"In truth, the boys up front did what they had to do to get us in front, Duncan [Watmore] had some great runs, showed great energy.
"But when required, the boys at the back didn’t do it.
"It’s happened too often, certainly in my time here.