Gausman and Ubaldo Jimenez are vying for the final position and, lately, Jimenez, who signed a four-year, $50 million contract a year ago, has outpitched the 24-year-old.
David De Jesus homered off Gausman to key a three-run third.
''I thought I was hitting a lot of spots. I think that one inning kind of got away from me a little bit. A couple of bounces different ways, and my line probably looks a lot different,'' Gausman said.
Manager Buck Showalter isn't saying whether Gausman will start, relieve or go to Triple-A Norfolk.
''Gausman was OK. Was working with a pretty tight strike zone,'' Showalter said. ''Pretty hitter-friendly day. Some hard-hit balls. I think it was actually kind of good for him today. He wouldn't look at it that way.''
Chris Davis' sixth-inning double scored Adam Jones for the Orioles' first run. Nolan Reimold homered for Baltimore in the eighth.
Everett Teaford, who was reassigned to minor league camp on Monday, started for the Rays, and pitched 3 2-3 scoreless innings, allowing three hits.
Bench coach Tom Foley managed the split squad for the Rays while Kevin Cash stayed in Port Charlotte to run the game against Boston.
Orioles: SS J.J. Hardy wasn't happy when he learned he would start the season on the disabled list with a left shoulder strain.
''That's a little disappointing, but I guess it could have been a lot worse. I feel better today than I did yesterday. At this rate, who knows how long it's going to be?'' Hardy said. ... OF David Lough (left hamstring) will also be on the DL at the beginning of the season. He also had back spasms. ''We think those two were related in the injury. At that point my hamstring wasn't 100 percent. Now my back is completely fine, it's just taking care of my hamstring and getting healthy,'' Lough said.
Rays: Teaford joked about starting after his demotion.
''The ol' reassigned from the reassignment - I don't know if that's ever happened,'' said Teaford, ''But hey, I felt like I did everything I could this camp to really put my best foot forward.''
Orioles: RHP Chris Tillman will make his second consecutive opening-day start, on April 6 at Tampa Bay.
Tillman was pleased with the assignment.
''It means a lot. I think when we've got five guys who are capable of doing it, that makes it that much more special. And I think every guy in here thinks the same way. We really do have five guys,'' Tillman said. ''There's only opening day, the first game, once and then the rest of the season it's our best guys going that night. I think as a group we all feel that way and I'm just excited to get this thing underway.''
Rays: Released INF Alexi Casilla. The veteran infielder had signed a minor league contract with the Rays last month.
Orioles: Acquired minor league C Audry Perez from Colorado for cash considerations. ... LHP Mark Hendrickson, who was released by Baltimore on March 16, has announced his retirement. Hendrickson, who pitched 10 seasons in the major leagues and four in the NBA, may pursue a career in professional golf.
Rays: LHP Jordan Norberto starts against the New York Yankees and RHP Chase Whitley in Tampa.
Orioles: Tillman will start against Pittsburgh LHP and Francisco Liriano on Wednesday.