John Viafara has moved along the south coast from Portsmouth to Southampton.
Viafara did not figure in Pompey boss Redknapp's plans
The 27-year-old Colombian international midfielder has joined Saints in a three-year deal for an undisclosed fee, although it is reported to be £750,000.
Boss George Burley said: "He is good in the air, very energetic and I'm sure he will give our midfield extra balance."
Czech midfielder Mario Licka, 24, has also signed after a trial. "He has good pedigree and we were fortunate to get him on a Bosman free," Burley added.
"I am delighted to have got both of these players who will give us extra options and cover in midfield.
"Viafara is a player I've been aware of since he went to Portsmouth. He's a regular international and was a regular when he first went to Pompey.
"He's very competitive, he can defend and is a good box-to-box player.
"Mario played three games on trial and did very well.
"He's an attacking midfielder with bags of energy. He is technically accomplished, comfortable on the ball and he loves to get forward."
The pair will be eligible to face Derby on Sunday subject to international clearance.
Former Pompey boss Alain Perrin signed Viafara from Colombian outfit Once Caldas in July 2005.
However, he failed to figure in current manager Harry Redknapp's plans and he had a spell on loan at Real Sociedad last season.