Morgan Spurlock - who directed the band's 'One Direction: This Is Us' documentary - has claimed that the 22-year-old singer, who left the group last month, was the stand-out performer in the band.
Morgan told TMZ: ''I think all those guys together were fantastic, they had something special but you cant fault Zayn for wanting to leave, people have to make their own decisions in life.
''I think Zayn is probably the most talented guy in the group, he's an incredible singer, all of them are talented singers but to make the decision to want to leave and go off on your own and chase a solo career in the midst of being as successful and as famous as you are, you can't fault someone for that.''
What's more, Morgan predicted Harry Styles will be next to leave the group.
He added: ''I think they'll stay together for a little while, for a little bit longer and then at some point Harry will leave he'll be next, and then I think Niall [Horan] and Louis [Tomlinson] and Liam [Payne], I think the three of those guys will become the new Bell Biv DeVoe [a 1990s group formed of the three remaining members of New Edition].''