The Bucks led 62-53 at the half and extended it to 93-76 entering the third quarter.
Milwaukee, which ranked 25th in the NBA last season with 24.7 3-point attempts per game, continued to fire away under new coach Mike Budenholzer. The Bucks were 17 of 47, with Antetokounmpo going 0 for 7.
WhatAntetokounmpo was doing was dunking.
Middleton had five 3-pointers, including a four-point play that put the Bucks up 111-88 with 5:03 remaining.
The Bucks were 14 of 34 beyond the arc in their 113-112 season-opening victory at Charlotte on Wednesday night.
The Bucks shook off a slow start en route to a 30-25 lead after one quarter, extending it to 62-53 at the half. Milwaukee took 26 of its 51 first-half shots from 3-point range, making eight.
Antetokounmpo had 22 points and 11 rebounds in the first half.