The competition for the fifth spot in Baltimore's rotation remains unsettled. Hernandez -- who allowed four hits, walked two and struck out six -- is trying to beat out Chris Tillman and Jason Berken.
"I would say we're going to go 15 rounds with it. We're going to go the distance," Trembley said. "We'll keep running these guys out there and try to make the right decision. Guys are answering the bell, they're making it real tough for me, and I like it."
After yielding three homers in 10 previous innings this spring, Hernandez did not allow an extra-base hit against Boston and lowered his ERA to 3.00. After the Red Sox loaded the bases with no outs in the fourth, the right-hander struck out Mitch Dening, Marco Scutaro and Josh Reddick.
"It's never fun with the bases loaded. I was trying to get out of there [allowing] one or two runs," Hernandez said.
Lackey extended his run of scoreless innings this spring to 13 before yielding RBI singles to Cesar Izturis and Felix Pie in the fifth. Slotted to be the No. 3 man in the Boston rotation, the right-hander concluded his performance with a perfect sixth.
"He gets it and throws it over the plate. We were real happy," manager Terry Francona said. "He continues to pound the zone. He stays down and is efficient."
Francona said Lackey finished his afternoon by throwing 15 more pitches in the bullpen.
Alan Embree, who signed a minor league contract with Boston last week, got two outs in the eighth but allowed three runs, two hits and a walk in his spring debut.
"I think you have back up and realize it's his first time out," Francona said. "Everybody else has been down here for a while and they look like it. The ball came out of his hand OK ... we've just got to get some reps under his belt."
Boston left fielder Jeremy Hermida left with right hamstring tightness, but Francona said it was a precautionary move.
"I don't think it was anything. It just didn't seem like a good thing to keep him in the game," Francona said. "He said, 'I feel it,' and I said, 'That's enough."
Boston's lone run came on a ninth-inning sacrifice fly by Tug Hulett.
Baltimore is 2-2 against the Red Sox this spring after going 2-16 against Boston last year. Saturday's win came two days after the Orioles pinned an 8-0 loss on the New York Yankees.
"Beating anybody is important," Hernandez said, "but if you can beat your divisional opponents over and over, that definitely builds confidence going into the regular season."