SCOTTSDALE, Ariz. — Randy Johnson looked like his old self against his old team.

Johnson struck out seven batters in three scoreless innings Tuesday in his first start against the Arizona Diamondbacks since leaving for San Francisco as a free agent this offseason.

The Giants overcame a 5-0 deficit to beat the Diamondbacks 7-6 before a crowd of 7,167 at Scottsdale Stadium.

Johnson gave up two singles and a walk and had his slider in top form. He recorded six of his strikeouts with the pitch he usually doesn't break out until later in the spring.

"Every time I go out, I need to kind of improve on things, and today it was maybe my slider," he said. "Next time, I can assure you I will throw a lot more off-speed pitches. Without a doubt, every time I go out there, there is an objective, whether it is stamina or pitches I am working on."

Johnson, 45, signed a one-year, $8 million contract with the Giants over the winter after spurning a $2.5 million offer from the Diamondbacks. He spent the previous two seasons, and eight overall, with Arizona.

"He had great command of his slider, and when he does that he going to strike people out," Diamondbacks manager Bob Melvin said.

Pablo Sandoval hit a two-run homer, his first of the spring, in a four-run sixth inning to tie the game at 5 for San Francisco.

Eugenio Velez hit his first homer of the spring in the fifth, and singled and scored the tiebreaking run on Freddy Guzman's two-out double in the eighth for the Giants.

Velez also made a diving catch in short left field to end the game, preventing the tying run from scoring from second base.

Conor Jackson and non-roster invitee Ryan Roberts had the hits for Arizona off Johnson.

"He threw the ball good," Jackson said of his former teammate. "For us, it is more of a comfort thing. I don't think any of us have ever faced him before. I think a lot of people are going to remember him as a Diamondback.

D-backs left-hander Doug Davis retired all six batters he faced despite being uncertain if he would start because of a nerve condition in his left arm that he said has bothered him for five years, although he has not spoken of it before.

"It's like a zinging down my arm," said Davis, who takes a prescription medication for the condition on the day he starts and the day before. "I've always had nerve problems, but they don't usually come on until the middle of April. When the muscle gets tight, it pinches the nerve. It started when I was in Milwaukee."

Miguel Montero added two hits, and Justin Upton had an RBI triple for Arizona.

Notes: Diamondbacks RHP Brandon Webb is scheduled to make his first start of the spring Wednesday at Tucson Electric Park against Team Mexico. Webb has been held out since feeling tightness in his right forearm while playing catch Feb. 26, the day before his first scheduled spring start against the White Sox. "It was a real minor thing, and to the point that now he is actually on a regular spring training schedule," Melvin said. "It hasn't been an issue since he was playing catch." Webb threw a bullpen session three days ago. ... Johnson had fun with before the game, sending a messenger to the Diamondbacks clubhouse to ask Jackson to pay after losing a small wager on the USC-California football game last fall. The message: "I wanted my money or he was going to have a rough at-bat," Johnson said. Responded Jackson: "That's why I swung at the first pitch. Jackson singled to right field. ... Giants manager Bruce Bochy was back at work Tuesday, with his right arm in a sling, after undergoing arthroscopic surgery on his right shoulder in San Francisco on Monday. ... Giants RHP Sergio Romo has a strained elbow and will not pick up a baseball for the next 10 days. Bochy said Romo still has enough time to regain his health before the start of the regular season. ... Giants OF Nate Schierholtz has a bulging disc in his lower back and is day-to-day.