"It's tough to put into words. It all happened so quickly," Hassan said after the Red Sox's 4-0 win over the Rays.
How much did he enjoy it?
"Probably the most fun I've ever had on a baseball field," said Hassan.
Hassan struck out looking in the first inning with the bases loaded, but he went 1-for-3 at the plate with a run scored on the day. He singled to right field in the fifth.
The 26-year-old played all nine innings in right field and didn't record an out. The closest he came was a James Loney ground-rule double in the fifth.
"It's great," Jon Lester said of watching Hassan and No. 4 prospect Garin Cecchini record their first Major League hits Sunday. "It kind of makes you reminisce on all your firsts."
The Red Sox selected Hassan out of Duke in the 20th round of the 2009 First-Year Player Draft, and he played 469 games over five years in the organization's system before getting called up Friday to replace an injured Ryan Lavarnway on the 25-man roster.
Hassan described himself as a contact, line-drive hitter. He's struggled with Triple-A Pawtucket at the plate, posting a .217/.318/.303 slash line. He's also struck out in 30 percent of his plate appearances.
For his career, though, Hassan has a .285/.393/.426 slash line and has hit for contact at every level.
"If he goes out and puts up the at-bats we saw in Spring Training, he's going to be just fine," manager John Farrell said. "He had probably some of the most consistent at-bats for the entire time that he was there with us."
Hassan said he feels more comfortable playing the outfield than first base defensively, but it's impossible to simulate playing in a Major League park, especially with the obscure outfield dimensions at Fenway.
"Getting used to a new park is always a challenge, but I'm going to try to do my best," Hassan said. "But a bunch of [veterans] have helped me with some defensive stuff and things to look for."