Manchester United signed Lammens from Royal Antwerp for £18M on deadline day, after deciding not to pursue Aston Villa's Emiliano Martinez.
With former first-choice goalkeeper André Onana on loan to Trabzonspor, Lammens now has the opportunity to compete with Altay Bayındır for a spot in the team under manager Ruben Amorim.
However, Lammens' brother Tom has admitted that he initially thought his brother should have joined Turkish club Galatasaray instead.
Tom explained that Galatasaray is a high-quality team that competes for trophies and offers the chance to make an immediate impact in the Champions League.
He also mentioned that many players at Manchester United had struggled with the pressure and weren't able to reach their full potential.
Despite these concerns, Lammens was convinced by Manchester United's goalkeeper scout, Tony Coton, who had been monitoring him for over a year.
Lammens was on the bench for Manchester United's recent defeat to Manchester City, but may have a chance to start in the team soon as he adjusts to the Premier League.
Manager Ruben Amorim may consider starting Lammens after the team conceded three goals, giving him time to adapt to the league.