I'd give some merit to the Bulls. They're a very energetic and physical team that gets the majority of their wins by out-hustling and out-running their opponents. It's difficult to match their intensity level, rest or no rest.
That said, if the Celtics defend the transition and pack the lane more not allowing them to get the ball into the paint (let the Bulls shoot from the outside, they will miss a lot of shots), it'll be very difficult for Chicago to stay in this game till the end.