The striker looked set to make a sensational Stamford Bridge return before Jose Mourinho hijacked the move, agreeing a five-year deal with the Belgium international at Old Trafford.
Conte's attention has since turned to Morata, a player he had a part in signing for Juventus shortly before resigning to take the Italy job in 2014.
However, Dortmund's Aubameyang has also been reported with a switch to west London, and it is the Gabon international, who struck 31 Bundesliga goals last season, which Chelsea legend Desailly believes is the better option.
“Morata, does he fit really? Does he hold the ball, does he have the speed of projection [Conte] is asking for?" Desailly said at the legends tournament Star Sixes.
“So it is a blow for him really [missing out on Lukaku].