Veljkovic, 19, joined Tottenham from Basel in his native Switzerland, though he's now choosing to represent Serbia having been capped at Under-17 and Under-19 levels.
The teenage centre back is highly rated in North London, and made his Premier League debut for Spurs by coming on as a substitute against Sunderland before also featuring against Aston Villa at the end of last season.
New manager Mauricio Pochettino has a history of developing young talent at both Espanyol and Southampton, with Victor Ruiz, Didac Vila, Luke Shaw, Calum Chambers and James Ward-Prowse all a testament to that - and he believed Veljkovic is a 'very good young player' having been impressed with him during pre-season.
Yet with the likes of Jan Vertonghen, Younes Kaboul, Federico Fazio and Vlad Chiriches above him in the pecking order, Veljkovic is set to leave on loan having confirmed that he will join Championship side Middlesbrough initially for three months, with the option of extending that to the end of the season.
"I’m leaving on a three-month loan," said Veljkovic. "Middlesbrough manager Aitor Karanka called me to talk about the possibility. He was previously an assistant to Jose Mourinho. I am happy to get the chance. In January a loan could be extended to the end of the season."
Getting the chance to play regularly in the Championship would be great for Veljkovic, particularly with a side that is used to winning - Middlesbrough have won six of their first 11 games this season, which leaves them just one point behind leaders Norwich as Spaniard Karanka looks to finally take them back to the Premier League.