Gallagher was among the most sought-after players available for loan in the domestic market during the summer transfer window.
Leeds, who were in search of a new midfielder, approached the Chelsea starlet and were keen on snapping him up, but Vieira’s Eagles ultimately won the race for his signature.
The Whites put together an impressive presentation to try to convince Gallagher to move to Elland Road, but he opted to join Crystal Palace because new boss Vieira gave him assurances that his attacking talents would be used to their full potential under him..
Gallagher spent last season on loan at West Bromwich Albion, but mainly occupied a defensive role at the Hawthorns and saw the Crystal Palace move as the right one for his career as he is keen on playing in a more advanced role this season
The 21-year-old, is a fixture under Vieira this season, and has been given license to be more involved in attack, which has paid dividends as he has scored twice in addition to registering an assist.
Chelsea boss Thomas Tuchel rates Gallagher highly and he is keen on returning to Stamford Bridge as a better all-round midfielder as he looks to step up his game further at Selhurst Park.
Leeds boss Marcelo Bielsa has been keen on bolstering his midfield in recent transfer windows and it remains to be seen whether the Whites will try to make any new additions in that department in the upcoming winter transfer window having missed out on Gallagher this summer.
