Ljajic is reportedly a long-term target for domestic rivals Milan and has yet to sign a new contract with Fiorentina, with his current deal set to expire in July 2014.
The Serbian was an integral part of Vincenzo Montella's side last season, scoring 12 goals in 31 appearances as Fiorentina narrowly missed out on qualification for the UEFA Champions League, Milan securing third place in Serie A on the final day.
Montella's men head into the clash with Ljajic's future still to be decided, but Mencucci is confident a resolution will be reached.
"We're near the end of the market and are nearing the end of the story," he told Corriere dello Sport.
"All possibilities are open. I am always optimistic and I'd like to see this deal being resolved for the best."
"I see him looking relaxed, even if being young it’s inevitable he could be affected by all this," Montella said.
Fiorentina start their Serie A campaign on Monday when they host Catania at the Stadio Artemio Franchi.
