Several names have been linked with the Teessiders over the last few weeks, while Warnock has admitted loan deals are the most likely before the deadline.
We’ve taken a closer look at some of the rumours which have been going around and the likelihood of them happening – scroll down and flick through our picture gallery to find out:
1. Danny Rose (Tottenham)
A surprising rumour which emerged earlier this week. The 30-year-old left-back is surplus to requirements at Tottenham and can only move to an EFL club following the end of the initial transfer window. Even so, Rose's wages will be well beyond what Boro can afford.
Photo: Michael Regan
2. Baba Rahman (Chelsea)
Another move which seems quite ambitious. Still, like Rose, the left-back's best chance of playing first first-team football appears to be a loan move to the Championship. Watford and Derby have also been credited with interest in the 26-year-old.
Photo: Srdjan Stevanovic
3. Nathaniel Phillips (Liverpool)
Boro have enquired about signing another centre-back, while Phillips, 23, looks set to leave Anfield in the next few days. A loan move may be possible, yet Phillips has also been linked with a permanent transfer, with Bristol City, Swansea and Nottingham Forest all credited with interest.
Photo: John Powell
4. Filip Benkovic (Leicester)
Another centre-back who will probably be allowed to leave on loan before Friday's deadline. Benkovic was on Boro's radar in January but instead moved to Bristol City where he made 10 Championship appearances. It's unclear if Boro would still be interested in the 23-year-old.
Photo: Harry Trump