The 23-year-old has joined the Championship club for the remainder of the 2018/19 campaign, and will look to help them maintain their blistering start.



Boro, under the guidance of Tony Pulis, are undefeated so far, winning four and drawing one of their opening five league games, while advancing to the third round of the Carabao Cup.



They trail only Leeds in the Championship, by virtue of goal difference, with the sides meeting at Elland Road this Friday.



McQueen, who can also play in midfield and who has made 29 first-team appearances for Saints since making his debut in 2014, joins up with the Teessiders ahead of that game, as he aims to aid their hopes of promotion this term.



Everyone at Southampton wishes Sam well for the season and will be monitoring his progress throughout the campaign.

Related Saints' Carabao Cup draw number