MILWAUKEE -- Talented veterans who spent years under the tutelage of coach Gregg Popovich turned the San Antonio Spurs into a model of success, but Monday night, it was a relative newcomer who set the tone for the five-time NBA champs.

Reserve shooting guard Jonathon Simmons scored a season-high 18 points on 6-of-7 shooting to lead the Spurs to a 123-98 rout of the Milwaukee Bucks at the Bradley Center.

"We've seen him do those types of things before," Popovich said. "He just go more minutes tonight."

Simmons, who spent the last three seasons in the NBA Development League before impressing the Spurs' brass during the Las Vegas summer league, was a force on both ends of the floor and helped make things difficult for Milwaukee's backcourt, which shot 14-for-35 from the field and 3-for-12 from beyond the 3-point arc.

"They got their hands on a lot of balls," Bucks interim head coach Joe Prunty said. "We were playing in a crowd, and it seemed like they were playing in space. When your spacing is right and you're moving the ball, the game becomes a little bit easier. Whether it was passes or dribbling, they were just getting more deflections."

On offense, Simmons paced a San Antonio unit that shot 54.4 percent for the game and got assists on 32 of 49 made baskets while hitting nine of 20 3-point attempts.

Seven San Antonio players scored in double figures, led by forward Kawhi Leonard's 24. Forward LaMarcus Aldridge added 16, reserve center Boris Diaw had 14, and forward David West and point guard Patty Mills each finished with 10. Mills started in place of Tony Parker (hip).

Center Tim Duncan finished with 16 points after being held scoreless for the first time in his career two nights earlier against the Houston Rockets. Duncan also grabbed 10 rebounds, dished out four assists and made two steals.

However, it was Simmons who left a lasting impression on both benches.

"My confidence comes from my work ethic," Simmons said. "I just try to make sure I do my work and that I'm ready to play."

All five Bucks starters scored in double figures. Shooting guard Khris Middleton led the way with 19 points, point guard Michael Carter-Williams had 16, center Greg Monroe added 15, forward Jabari Parker scored 14 and forward Giannis Antetokounmpo had 11.

However, the Bucks struggled to score in the second half after making 51 percent of their shots in the first two quarters.

"They're a big, physical team," Middleton said. "They did a good job of keeping us off the glass, and that killed us."

Early on, the Bucks were hot. They shot 76 percent from the field and led 30-29 after one quarter.

A 17-1 run and nine first-half offensive rebounds -- contributing to 12 second-chance points -- sent the Spurs into the break up 60-49.

"They move the ball," Monroe said. "They play good defense. They have a championship pedigree. They know what it takes to win. Every night, they come out and do it. Every night, they play hard. They play together. They trust each other."

Milwaukee was forced to play the second half short-handed after reserve guard Jerryd Bayless went to the locker room with a sprained left ankle.

Bayless missed the Bucks' previous 19 games because of a sprain in the same ankle. His status moving forward was uncertain.

"We've been through it before," Prunty said. "It's always been a next-man-up mentality, and that won't change. Everybody's got to be prepared."

NOTES: Bucks SG O.J. Mayo was fined $25,000 by the league Monday for his outburst Saturday in Milwaukee's 95-85 victory at Minnesota. Mayo was ejected from the game in the first quarter after picking up two technical fouls, then charged after referee Eli Rose before finally leaving the court. ... The Spurs beat the Bucks 95-70 in San Antonio last month, and they have beaten Milwaukee eight times in a row. ... Bucks interim head coach Joe Prunty began his NBA coaching career as an assistant on San Antonio head coach George Popovich's staff from 1996-2005. ... Spurs PG Tony Parker did not travel with the team to Milwaukee as he recovers from right hip soreness. Parker's average of 12.4 points per game ranks third on the team, and he is sixth in the league with a 3.22 assist-to-turnover ratio.