With Ramon Sessions taking over at starting point guard, the Cavs jumped out to a 17-2 lead on the Bucks behind Sessions' three assists in the first five and a half minutes.
The Bucks came storming back, though, to outscore the Cavs 26-8 in the final six and half minutes of the quarter.
In the second quarter, the Cavs got back to the basketball that put them up 17-2 early, outscoring the Bucks 32-25. Sessions had 10 assists in Irving's stead.
Ersan Ilyasova of the Bucks led all scorers with 12 points.