While Boro can't buy or loan any new players until the summer, they could still bring in a free agent or two, should they wish to bolster their squad further. Here's a look at some of the intriguing options still out there, who could yet be picked up:
1. Sandro
Could a return to England be on for the former QPR and Spurs midfielder? Probably not, in truth. After spells in Turkey and Italy, the globetrotter was last at Brazilian side Goias. Photo: Paolo Rattini
2. Pape Souare
The Senegal left-back is on the search for a new club after leaving Ligue 2 outfit Troyes. His wages would probably be far too high, but hey, you never know... Photo: AFP Contributor
3. Aron Johannsson
Formerly of Werder Bremen and AZ Alkmaar, the ex-USA international striker is looking for his next big move, after reigniting his career in the Swedish top tier last season, scoring 15 goals for Hammarby IF. Photo: PATRIK STOLLARZ
4. Ikechi Anya
Released by Derby County at the end of last season, the Scotland international is yet to be snapped up. He's a highly-versatile footballer, capable of playing as a winger or further back the field as a full-back. Photo: Alex Pantling