"Everything was coming out sharp and firm," Lambo said. "You definitely didn't see a guy that's coming off of surgery, that's for sure. He looked ready to go. He seems like a guy that's very passionate and wants to get out there and play."
"He looked really good," A's manager Bob Melvin said, "and he was excited, too."
Alvarez will increase his pitch count to 30 when he throws to hitters again on Sunday in a scheduled two-inning simulated session with Class A Advanced Stockton.
"I felt good," Alvarez said through translator Alex Arpiza. "I felt relaxed. I felt like I always do when I go to the hill. Very happy to get in there and take off right where I left off."
"I didn't really know what to expect," Canha said, "but his velocity was really good."
Alvarez isn't so much honing his focus on velocity right now so much as he is on maintaining his health, and to this point his rehab has gone extremely smoothly, leading the A's to believe they'll have the All-Star pitcher in their rotation in late May, "if there are no hiccups along the way," Melvin said.
"It's probable," Alvarez said, "but I'm just preparing myself to get here as quick as possible.
"I'm happy to be back on the hill, just trying to regain that rhythm, that groove that I had before."
Alvarez, 25, was the Marlins' Opening Day starter last year but compiled just 22 1/3 innings while pitching to a 6.45 ERA ahead of his season-ending surgery. He was outstanding for them the year before, though, finishing with a 2.65 ERA in 187 innings.
Jane Lee is a reporter for MLB.com. Follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.