"It's been a journey," said the 29-year-old Rivera. "I've been pretty up and down in my career."
But Saturday, when he was informed he was being promoted to the big league club, was an "up" day for him, even if it came at the expense of another catcher, as Yasmani Grandal went on the 60-day disabled list with damage to ligaments in his right knee.
Grandal suffered the injury Saturday when the Nationals' Anthony Rendon slid into his knee on a force play at the plate.
Rivera, who signed with the Padres in December as a Minor League free agent, was hitting .343 with five home runs with Tucson. He becomes the backup to Nick Hundley.
"This time I feel like I earned it," said Rivera, who played parts of three seasons with the Mariners and in 45 games with the Twins in 2011. "I worked hard all season."
To get to Washington in time for Sunday's game, Rivera flew on Saturday from Tucson to Phoenix, took a red-eye flight from Phoenix to Philadelphia, and then a third flight to Washington. He landed at 9 a.m. ET.
Rivera had an out-clause in his contact where he could have left the organization on June 15 if a better opportunity presented itself. But, he said, loyalty to the organization made it easy for him to stay put.
"I've got to give a lot of credit to San Diego. I had been a backup at Triple-A the last few years, but they gave me the chance to go down and play every day. You have to appreciate that."
San Diego manager Bud Black said the reports on Rivera from his time in Tucson have been good -- his ability to handle the pitching staff and what he's done at the plate.
"The main thing is he's using the whole field," Black said of Rivera. "He's an aggressive hitter. He's not tentative."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. Andrew Simon is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.