Those hopes have been dashed.
Loaiza was with the team Monday for Opening Day at Safeco Field, but general manager Billy Beane on Monday told MLB.com that Loaiza will fly back to the Bay Area on Tuesday morning in the wake of less-than-positive results from a weekend MRI exam.
"It's inconceivable that he won't miss at least two [turns]. Conceivably more," Beane said. "There's a little activity in there they want to quiet down before he throws again."
Loazia said he didn't even try to throw before Monday's game.
"It's still not right," he said. "I'm seeing a doctor tomorrow, and we'll go from there."
Loaiza, who spent more than a month on the DL with a strained left trapezius last season, has been replaced in the rotation by righty Chad Gaudin, who will make his season debut Thursday in Anaheim.
Beane wouldn't say if the delay in Loaiza's return meant a second start for Gaudin, who spent all of last season working out of the A's bullpen.
"That's for [manager Bob Geren] to decide," Beane said. "We'll see. But we will need someone for that spot at least twice. Hopefully no more."
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.