Having added Eljero Elia earlier in the window, manager Ronald Koeman was not planning to bring in any new faces to St Mary's.
However, mounting injury problems and Jack Cork's move to Swansea has led Saints to act, with Serbia international Djuricic arriving on loan until the end of the season.
The 23-year-old joins Southampton from the Portuguese giants, having ended a loan spell at Mainz in the Bundesliga.
"I know the player from Holland," Koeman told the club's official YouTube channel.
"He played several seasons for Heerenveen and then he moved to Benfica.
"It's a young player, he's 23 years old, he's technical, fast and he can play in different positions in the midfield
He can play on the left side and the right side.
"It's part of the philosophy of the club; young players
He was in a difficult situation, he was on loan at Mainz and we will take him on loan for the rest of the season.
"It's a good possibility for him, and for us it's one more player who can play in different positions
It's always best for the coach to have more possibilities in players who can change positions.
"The last few weeks we have had problems to score goals, like Sunday.
"We created good opportunities and you have to score, always it's easy to have really good competition."
Djuricic spent time in the youth systems of Radnicki Obrenovac, Red Star Belgrade and Olympiacos, before returning to hometown club Obrenovac.
The attacking midfielder subsequently moved to Heerenveen and then Benfica, before being loaned to Mainz for the first half of this season.
Djuricic made 12 appearances in all competitions for the German side before linking up with Serbia team-mate Dusan Tadic at St Mary's.
Source : PA
Source: PA