Puel is poised to succeed Ronald Koeman at St Mary’s this week after spending four years at Nice, who he guided to fourth place in Ligue 1 last season.
The 54-year-old won the French top-flight title in his first full season of management at Monaco, where he spent 24 years as a player – under Arsenal boss Arsene Wenger – and a coach.
He went on to enjoy six years at Lille before taking charge of Lyon, leading them to the Champions League semi-finals in 2010.
Mane, meanwhile, was due on Merseyside today to become Liverpool’s second-most expensive player, after £35m Andy Carroll.
The Senegal forward is the summer’s third major departure from Southampton, following midfielder Victor Wanyama’s £11m move to Tottenham and Koeman’s switch to Everton.
Southampton, who have already mitigated Mane’s exit by signing £11m winger Nathan Redmond from Norwich, have also sold Nathaniel Clyne, Adam Lallana, Dejan Lovren and Rickie Lambert to Liverpool since 2014.
Signing Mane will take Liverpool's outlay on Southampton players alone to £95.5m in just two years.