"It was quick. That's what I wanted. Get there, throw a lot of strikes and get quick outs," said Walker, who threw 20 additional pitches in the bullpen after he left the game.
Lopez made his second Cactus League start for the White Sox, his first since allowing five runs and four hits in 1 1/3 innings on Feb. 28 against the Reds. He was one of three players acquired from the Nationals in the trade for Adam Eaton on Dec. 7.
"I felt good. I improved, pitched a lot better than the last time," said Lopez, who threw three innings, allowing a run on three hits with three strikeouts, two of which came against D-backs slugger Paul Goldschmidt. "I had much better focus than the last time. I kept my pitches down, which was good."
Oswaldo Arcia, the former top prospect signed by the D-backs to a Minor League contract in December, took an Aaron Bummer fastball to the opposite field, landing on the right-field berm in the fifth. Jake Lamb had an RBI double in the first for the D-backs, and Ildemaro Vargas added a solo home run in the seventh.
The White Sox only run came on a Tyler Saladino homer against Tom Wilhelmsen in the fifth that briefly tied the game before Arcia's long ball.
White Sox Up Next: The South Siders have a Cactus League game against the Padres on Monday at Camelback Ranch before Tuesday's off-day. In the 2:05 p.m. CT clash, veteran James Shields will make his second start of the spring. He allowed a run on two hits and struck out two against the D-backs on Wednesday.
D-backs Up Next: Left-hander Robbie Ray will make his second start this spring when he faces the Royals at 1:05 MT Monday in Surprise, Ariz. Ray walked three in 1 1/3 innings in his first start but did not give up a hit or run. Right-hander Matt Koch is scheduled to make his first appearance this spring.
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Chris Gabel is a contributor to MLB.com.
Barry M. Bloom is a national reporter for MLB.com and writes an MLBlog, Boomskie on Baseball. Follow @boomskie on Twitter.
This story was not subject to the approval of Major League Baseball or its clubs.