MESA, Ariz. -- After getting tips on how to throw his slider from Hall of Famer Randy Johnson earlier in camp, Sean Manaea couldn’t wait to implement the changes. Getting his first chance to face hitters on Wednesday, the improved pitch was unleashed.

“Randy must have had an effect on him,” A’s manager Bob Melvin said of Manaea. “Good slider today. He looked good.”

Part of Johnson’s advice to Manaea during a visit to the A’s training complex at Fitch Park on Sunday included ways to manipulate the slider and when to use it in order to throw the hitters' timing off. There were three sliders Manaea felt he executed to perfection on Wednesday, one coming on a strikeout and the other two for swinging strikes.

“I threw three really good ones that I felt were really competitive,” Manaea said. “I feel like it had been a little bit harder for me recently to throw it consistently for strikes. Just being able to throw it for strikes and seeing that shape is huge. I felt like I filled up the zone today and just overall felt like I was really good.”

Manaea also showed off his defense on Wednesday, making impressive grabs on a pair of comebackers.

“He told me he’s going to be a Gold Glover this year, too,” Melvin said. “He fielded two balls off the bat very well and pointed to me both times. I don’t know that he’ll win a Gold Glove. It’d be a nice challenge for him, but I think he can make some strides on defense.”

Winning a Gold Glove Award is one of a few personal goals Manaea has for his career.

“Obviously, the Cy Young is a goal. But in my career, 100 percent, two things I really want to do is win a Gold Glove and hit a home run,” Manaea said. “You have to put it out there. Why can’t I win a Gold Glove? It’s going to happen at some point.”

Murphy to miss start of Cactus League
As Sean Murphy eases his way back from offseason knee surgery, the A’s have been giving the catcher a lighter workload in the early part of spring. They plan to hold him out of the first few games, targeting March 2 for his Cactus League debut.

Murphy’s absence will give the A’s a chance to get a better look at their other catchers in camp, mainly Austin Allen and Jonah Heim, both of whom are candidates to make the Opening Day roster as the backup catcher. Heim is the A's No. 21 prospect, according to MLB Pipeline.

“We have some competition for the backup spot,” Melvin said. “Jonah Heim had a really good year last year. I don’t think Austin wants anything handed to him. He wants to earn it. We traded a pretty good player for him. He’s a guy we wanted here. Our front office people like the bat, so he’s here to earn a job.”

Puk to start Cactus League opener
The A’s plan to start A.J. Puk in their Cactus League opener against the Cubs on Saturday. With the club playing split-squad games against the Giants and D-backs on Sunday, Melvin said Mike Fiers and Chris Bassitt will both get a start that day.