Jakubauskas will pitch Sunday if Jeremy Guthrie hasn't sufficiently recovered from a high fever that forced him to miss his last scheduled start.
"[Jakubauskas] could go six to seven tomorrow if we need it," manager Buck Showalter said.
The 32-year-old right-hander was assigned to the bullpen for Saturday's doubleheader against the Rangers.
"All I've been told is I'm an emergency arm for [Saturday] and [Sunday] will be handled later," Jakubauskas said. "I'll take whatever they give me."
Bergesen started one game this season, allowing two runs in 3 2/3 innings in a loss to Detroit. He was struck by a line drive during a spring training game and thrust into the rotation because of an injury to Brian Matusz and Guthrie's illness.
"I don't think he's pitched more than four innings in 20 days. It's time for him to get down there and get his feet back on the ground," Showalter said. "He had a lot of things thrown at him there with the line drive, with Matusz being out, with Guthrie's health. We need a starter tomorrow potentially if Guthrie can't go and Bergy's only had three days rest."
The 32-year-old Jakubauskas appeared in five games for Baltimore in spring training, allowing no runs and four hits in 6 1/3 innings.
"I threw well in the spring, but a lot of guys threw well in the spring," he said. "I have three camps under my belt and I've never seen so many guys throw the ball so well through an entire camp. My thing was, do your job at Triple-A and be one of the first guys called up. That happened, so I'll try and stay up here as long as I can."
In 36 career games with Seattle and Pittsburgh, the right-hander is 6-8 with a 5.48 ERA.
In other news, Orioles second baseman Brian Roberts was in the starting lineup for Saturday's first game after undergoing tests in a hospital Friday night for stomach pain.
"Everything's fine," Roberts said. "I haven't been feeling great for a couple days and the doctor wanted me to go get checked out. He just wanted to rule out appendix and all that junk."