Scottish champions Celtic signed Australia midfielder Aaron Mooy on a free transfer and German defender Moritz Jenz on loan from Lorient on Tuesday.
Former Brighton midfielder Mooy agreed a one-year contract with the Hoops after leaving Chinese club Shanghai Port earlier this year.
The 31-year-old, who had a spell in Scotland's top-flight with St Mirren more than a decade ago, previously played under Celtic boss Ange Postecoglou during his time in charge of the Australia national team.
Mooy has joined Celtic with a view to nailing down a place in the Socceroos squad for the World Cup in Qatar later this year.
Just minutes after announcing the signing of Mooy, Celtic revealed they had recruited Jenz on a season-long loan from Ligue 1 side Lorient.
"I'm delighted that we've been able to bring in both Aaron and Moritz to the club and I'm sure they'll be great additions to our squad," Postecoglou told Celtic's website.
"I obviously know Aaron from my time coaching the Australian national team and he brings with him a wealth of experience at both club and international level.
"Moritz is a player we've been aware of for a while now and I'm pleased that we've been able to sign him."