Former England international Lallana agreed a three-year contract with Brighton just 24 hours after the end of the Premier League season.
The 32-year-old, whose deal with Liverpool expired after their final game on Sunday, was targeted by Everton, Leicester and Burnley before opting to join Graham Potter's side.
He explained in his presentation for the club that what pushed him to join the club was "the chairman's ambition and how highly regarded the manager is" after managing to keep Brighton in the Premier League for another season.