Examined on Tuesday by Dr. Phil Kwong of the Kerlan-Jobe Orthopedic Clinic in Southern California, Morales was found to have "soreness" in the foot in a Magnetic Resonance Imaging, according to Angels general manager Tony Reagins.
Morales, who played 51 games last year before fracturing his lower left leg on May 29, will open the season on the 15-day disabled list.
His primary replacement at first base will be Mark Trumbo, who has had a brilliant spring and is bouncing back from groin tightness. Trumbo returned on Tuesday after sitting for four days and had one at-bat before rain canceled a game against the Cubs.
"We would prefer he's ready, like anybody," Reagins said of Morales, who placed fifth in the 2009 American League Most Valuable Player balloting. "But we understand the significance of the injury. When you put it in that context, you have to be smart.
"We have a long season ahead of us. If we can be conservative and smart on the front end, hopefully it benefits us in the long run."
Reagins does not expect Morales to miss extensive time.
"I'm really confident in saying he's going to be back in relatively short order," he said. "I'm not anticipating him being out for months."
Morales has been hitting and fielding for several weeks and seemed to be moving toward a return for the season opener on March 31 in some capacity when the foot issue flared up last week.
He ran for two days in a row, going through bases without turns on the second day, but turned up sore on Thursday and has not run since then.
Soreness in the ankle and foot has prevented Morales from performing flexibility and range of motion exercises, and he is "day to day" until he can "tolerate more pressure on the ankle," Reagins said.
Manager Mike Scioscia said Morales is "taking a half-step back to take a step forward.
"It has to do with the ball of his foot, not the ankle. We're going to let it calm down and get back to baseball activities. We had some tests done. Hopefully, it's something very manageable."
Trumbo, 25, has been pounding baseballs since last April, starting with Triple-A Salt Lake when he led the Pacific Coast League with 36 homers, 122 RBIs and 103 runs scored, batting .301. He was only 1-for-15 in September cameos for the Angels but continued to flourish in the Venezuelan Winter League.
Trumbo is batting .340 in the Cactus League with five homers, five doubles and 13 RBIs in 47 at-bats.
"I would say he's met expectations," Reagins said. "Spring Training is Spring Training. He's been able to perform at a high level against very good pitching early in games, which is good to see."You still have to do it on the Major League level, in season." There is only one way to find out, obviously.
"You've got to play," Reagins said.
Also on the depth chart at first are Brandon Wood, Howard Kendrick, Bobby Wilson and Chris Pettit.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.