Ivanovic scored in last night's Europa League final win over Benfica.
"This is why the trophy is so important," he told the London Evening Standard. "We can improve a lot next season and a trophy will give the new players a lot of extra confidence. They will prove to themselves that they are top quality players.
"To see Sir Alex go was a surprise for everyone and a big loss for football. Man United won't change a lot, the strategy of how they play. But it's now going to be very interesting in the Premier League next season.
"I think the next Chelsea manager will build the team and I hope we will improve. This season has been very long and hard and to do it the squad has to be good enough but I hope we will have the quality to fight for the title."