Giannis Antetokounmpo had 21 points and 13 rebounds to lead the Bucks to a 90-88 victory over the Philadelphia 76ers on Thursday night.
Wesley Matthews hit the 3-pointer winner with 23.8 seconds left.
Lopez tallied 17 points as the Bucks, who went 0-5 in the preseason, won their season opener after Matthews surprised the Sixers on the long 3. James Harden, who scored 31 and rallied the Sixers in the fourth, missed a jumper that could have won the game.
Tyrese Maxey added 15 points for the Sixers. Joel Embiid was shut down by Lopez and Antetokounmpo and did not score in the second half. Embiid finished with 15 points and 12 rebounds.
The 76ers lost their opener Tuesday night in Boston and had another weak defensive effort early that had the Philly crowd booing them off the court in the third quarter.