SAN DIEGO -- Anthony Rizzo hit a two-run home run against his old team and Jake Arrieta pitched seven strong innings to lead the Cubs to a 5-1 victory against the San Diego Padres on Thursday night.
Arrieta (1-0) held San Diego to one run and four hits, struck out seven and walked one. He was activated May 3 after beginning the season on the disabled list with tightness in his right shoulder and came in with a 2.70 ERA in three starts.
San Diego lost its fourth straight game. It was the 15th time in 48 games the Padres scored one or no runs.
The Padres were shut out for the eighth time -- most in the majors -- on Wednesday night, losing 2-0 to Minnesota.
Rizzo put the Cubs ahead 2-1 in the fourth with a 417-foot homer into the sandy play area beyond the fence in right-center, his eighth.
Junior Lake was aboard on a bunt single down the third-base line, the Cubs' first hit of the night off lefty Eric Stults.
Rizzo was with the Padres part of the 2011 season before being traded to the Cubs in the deal that sent right-hander Andrew Cashner to San Diego.
The Cubs chased Stults in the fifth with three runs and four hits. Nate Schierholtz hit a leadoff double and scored on Darwin Barney's single to center. Arrieta sacrificed Barney, who scored on Emilio Bonifacio's single to right. Lake doubled over center fielder Cameron Maybin's head to bring in Bonifacio.
Carlos Villanueva pitched the final three innings for his first save this season.
San Diego's only run came on Seth Smith's two-out homer to right in the first, his team-leading sixth.
Stults (2-5) gave up five runs and six hits in 4 2-3 innings, struck out four and walked none.
The Padres wore replica uniforms from 1984, when they beat the Cubs in the NL championship series to reach the World Series for the first time.
Cubs manager Rick Renteria spent the previous six seasons on San Diego's coaching staff.
NOTES: The four-game series continues Friday night when Cubs RHP Edwin Jackson (3-3, 3.98) faces Padres RHP Tim Stauffer (1-0, 2.41), who will be making his first start of the season. ... Padres LHP Robbie Erlin, who had been scheduled to start Friday night, went on the 15-day disabled list with a sore left elbow, retroactive to Sunday. He is 3-4 with a 4.53 ERA in nine appearances, including eight starts. To take his spot on the roster, the Padres selected RHP Blaine Boyer from Triple-A El Paso.