Liverpool midfielder Allan has joined Cypriot club Apollon Limassol on loan for the season, while winger Ryan Kent will play for Freiburg.
Allan, 20, joined Liverpool in 2015 and was on loan at German club Hertha Berlin last season.
Towards the end of that campaign, Hertha sporting executive Michael Preetzsaid the club hoped to keep the Brazilian for another season.
Allan has yet to make a senior appearance for Liverpool and has also had loan clubs with Finnish side SJK and Sint-Truiden in Belgium.
Kent, 20, recognises the importance of this season in his career and will spend the 2017-18 campaign in the Bundesliga as he seeks regular first-team football.
The Liverpool winger is set for his third spell out on loan after time at Coventry City and Barnsley on a temporary basis.
Kent, who also drew interest from Hannover 96, signed a long-term contract at Anfield earlier this month and was recently singled out for praise by manager Jurgen Klopp for his development.
After Kent featured in seven of Liverpool's eight preseason friendlies, Klopp said: "Ryan Kent, I know him one and a half years. Last year he developed unbelievably and this preseason is completely different to last preseason."
Meanwhile, Liverpool academy forward Toni Gomes has joined League Two side Forest Green Rovers on loan for the rest of the season.