Liddi, 23, was recalled from Triple-A Tacoma on Tuesday and manager Eric Wedge penciled him into the lineup for the first time on Wednesday. He batted ninth.
"I was thinking about what I wanted to do, and it was either going to be today or this weekend," said manager Eric Wedge. "So I figured, let's just get him in there and knock that first one out."
Liddi said that the previous 24 hours had been hectic, between flying to Anaheim to join the team and having his phone blowing up with messages from friends. But he tried to keep his routine as normal as possible on Wednesday.
He didn't know that he would be playing until he got to the ballpark in the afternoon.
"I came in and saw the lineup and was really happy," he said. "We'll see what happens."
His initial feeling?
"Excited," he said. "Probably nervous a little bit, but normal. I'll have to try to be calm. It'll be a big impression for me. I'll try to calm down and do what I need to do."
Liddi hit .259 with 30 home runs, 104 RBIs and a Pacific Coast League-leading 121 runs scored with the Rainiers.
Six Italians have previously played in the Majors, the last being Reno Bertoia in 1962. But those six all moved to North America as kids.
Liddi grew up in Sanremo, Italy, and will be the first graduate of the MLB European Academy to play in the Majors.
His debut is thus awaited by a following in Italy, as well as his own circle of supporters.
"The last day a lot of people tried to get hold of me, all my friends and family," Liddi said. "It's been good to see that people care about me and want me to do good."