CINCINNATI -- Travis Wood got his first win in months and impressed his former pitching coach along the way.
Wood (8-11) struck out five and walked one in his first victory since he pitched eight innings in a 3-0 win at Philadelphia on June 15. The left-hander, who made the All-Star team last season, was 0-6 with a 5.45 ERA in his previous 12 starts.
"That was nice," he said. "My command was good. I was able to keep the ball down in the zone and get some quick outs."
Cincinnati was shut out for the 12th time this season. Johnny Cueto (15-8) struck out eight in 6 1/3 innings in his second straight loss after winning seven consecutive decisions.
Wood improved to 2-5 with a 3.30 ERA in nine career starts against the Reds.
"He was commanding both sides of the plate with his cutter," said Cincinnati manager Bryan Price, who was the pitching coach when Wood was with the Reds. "He didn't give us anything good to hit."
Rizzo went deep with two out in the first, driving a 2-1 pitch into the seats in right. He joined Miami's Giancarlo Stanton as the only two National Leaguers with at least 30 home runs.
Starlin Castro, in his first game back from the bereavement list, followed with a single as the rain increased, forcing a 50-minute delay just five minutes into the game.
Cueto blamed the rain for Rizzo's home run.
"I was upset," he said with catcher Brayan Pena serving as his interpreter. "They knew it was going to rain. They should've called timeout and not started the game. I was afraid I was going to hit him with a pitch. I couldn't grip the ball."
Wood stayed loose by throwing in the cage about every 15 minutes. That work, plus throwing 96 pitches, led to manager Rick Renteria lifting him.
"To be honest, that was an easy decision," Renteria said.
Alcantara followed Matt Szczur's leadoff single in the seventh with his fifth homer of the season and second in two games. He also homered on Sunday against Baltimore in Chicago's final home game before embarking on a seven-game, six-day road trip.
Tuesday's 50-minute rain delay was the 21st for the Reds this season.
The Cubs have hit at least one home run in 10 consecutive games for their longest such stretch since a 10-game run from Aug. 2 through Aug. 12, 2011.
RHP Daniel Corcino celebrated his 24th birthday by making his major league debut, pitching the ninth for Cincinnati. He was recalled from Double-A Pensacola on Friday.
Cubs: RHP Jacob Turner makes his first start for Chicago after two relief appearances since being acquired from Miami on Aug. 8.
Reds: RHP and new father Mat Latos, hurt by blown saves in two of his last three starts, makes his second start of the season against Chicago.
Cubs: RF Ryan Sweeney left after the top of the second. He grabbed his left hamstring while running out a grounder. Rizzo left the game in the eighth with lower back tightness.