The Raptors were led by 19 points from Serge Ibaka and 14 points from Cory Joseph, starting in place of Lowry. He scored the first nine points of the game and had 21 in the first, the most by a Raptors player in a quarter this season.
Eric Bledsoe led the Bucks with 29 points. DeMar DeRozan had 11 in the loss. Jabari Parker (left knee surgery) and Mirza Teletovic (pulmonary emboli) are out for the Bucks.
The Bucks (19-15) were visiting Toronto for the first time since the opening round of the 2017 National Basketball Association playoffs, when the talented young squad led by 6-foot-11 phenom Antetokounmpo got the NBA's attention by going up 2-1 on the favoured Raptors before Toronto won in six. The team has won 11 in a row at the ACC, tying their second-longest streak at home.
The Raptors also tied a franchise record with their 12th straight win.
The Milwaukee Bucks look for a big victory after splitting their last eight games.
DeRozan is the third player in Raptors history to score 50 or more in a single game. Toronto was on the road for January 1 last season, defeating the Los Angeles Lakers 123-114 at Staples Centre.
In a rematch of last spring's first-round playoff series, the Bucks hunted the Raptors down in the final five minutes or regulation time, taking a four-point lead with just over two minutes remaining.
Toronto Raptors guard DeMar DeRozan became the first player in National Basketball Association history to score at least 50 points on New Year's Day and set a franchise record with 52 points in Monday's 131-127 win over the Milwaukee Bucks. Giannis Antetokounmpo is averaging 29.1 points and 10.4 rebounds while Khris Middleton is averaging 20.5 points and 4.4 assists. DeMar DeRozan is averaging 24.1 points and 4.3 rebounds while Kyle Lowry is averaging 15.9 points and 7.1 assists.
In the 10-game stretch that began Monday, Toronto will face elite teams - Golden State, Cleveland and San Antonio - along with surprising Detroit, red-hot Chicago with a road game against the Bucks thrown in.