Ramirez signed a minor league deal with an invitation to spring training last week. The 39-year-old outfielder/designated hitter, who wore No. 24 for most of his career and No. 99 when he played for the Los Angeles Dodgers, will wear No. 1 with the A's.
"Everything starts with the number one. To me, it's like a new beginning," Ramirez told ESPNDeportesLosAngeles.com after his arrival at Municipal Stadium. "God has given me a second chance and I'm not going to waste it. My arrival in Oakland is not a coincidence, it's a God-incidence."
Ramirez, who twice has tested positive for drugs banned by Major League Baseball, will have to sit out for 50 games before having his first at-bat this season. Barring rainouts, his debut could come May 30, when he turns 40, at Minnesota.
After taking batting practice, during which he hit at least seven home runs off A's coach Mike Gallego, Ramirez addressed the media, accompanied by his wife, Juliana, and two sons, Manny Jr. and Lucas.
"I made some mistakes and I want to show my children I can correct them," Ramirez said. "Every Thursday morning my wife and I went to church, kneeled down and prayed. I am blessed to have this opportunity again."
Ramirez decided to retire after he was suspended in April 2011 while playing for the Tampa Bay Rays, but he reversed that decision and was reinstated in December.
"I'm a new man who found true happiness in God's word. Right now, I have a peace I never experienced in my life," said Ramirez, a .312 lifetime hitter with 555 home runs and 1,831 RBIs in 19 seasons.
"Sometimes you don't appreciate what you have until you lose it, and that's what happened to me," Ramirez said. "Now I appreciate my family more, my kids, the game. I've got a beautiful wife, I've got my kids, my family and I'm getting my career back. It's been a blessing."
Ramirez said he has no expectations other than to "show people I can still play."
A's manager Bob Melvin said someone of his stature could influence the rest of the team.
"He can be a great example with his work ethic," Melvin said. "We have some young kids and, who knows, maybe something will rub off."
There was a buzz in the A's clubhouse the moment Ramirez walked in and sat in front of his locker. His new teammates warmed up to him quickly as introductions were made around the room.
Everybody stopped what they were doing to watch Ramirez take batting practice. Melvin was certainly impressed in the little he saw of it.
"I saw all I needed to see," he said. "I saw the one ball he hit off the center-field wall. He truly is one of those guys who has the mechanics of his swing right away. Rarely do you see him off balance."
Enrique Rojas is a baseball writer for ESPNDeportesLosAngeles.com. Information from The Associated Press was used in this report.