BALTIMORE -- The Baltimore Orioles and Tampa Bay Rays both made significant late additions before their showdown at Camden Yards.

The Orioles called up outfielder Heston Kjerstad from Triple-A Norfolk on Thursday, adding another top prospect to the big league club hours before starting a huge four-game series against Tampa Bay. The Rays activated outfielder Manuel Margot from the injured list after he had been sidelined by a right elbow problem.

The Orioles led Tampa Bay by two games atop the AL East heading into this set. It's the last time the teams face each other in the 2023 regular season.

Kjerstad was the No. 2 pick in the 2020 amateur draft, and he is ranked 49th in ESPN insider Kiley McDaniel's latest top 50 prospects. He hit .298 with 10 home runs and 32 RBIs in 76 games at Norfolk.

The Orioles called him up after slugger Ryan Mountcastle left Wednesday night's loss to St. Louis with a shoulder issue. In addition to selecting Kjerstad's contract, Baltimore recalled right-handed reliever Bryan Baker from Norfolk and optioned outfielder Ryan McKenna and left-hander Nick Vespi to Norfolk.

The Orioles recalled utility man Terrin Vavra from Norfolk and put him on the 60-day injured list with a strained right shoulder.

Kjerstad joins a Baltimore team led by second-year catcher Adley Rutschman and rookie infielder Gunnar Henderson. Right-hander Grayson Rodriguez and infielder Jordan Westburg are among the highly regarded prospects the Orioles have promoted this year.

Margot has hit .249 in 85 games this season for the Rays. He returns to a team that's been able to stay within striking distance of the Orioles despite missing several key players.

Ace Shane McClanahan had Tommy John surgery last month, and star shortstop Wander Franco has been on administrative leave while authorities in the Dominican Republic investigate him for an alleged relationship with a minor. Right-handed reliever Jason Adam (left oblique strain) and outfielder Jose Siri (right hand fracture) went on the IL earlier this month.

The Rays optioned infielder Vidal Bruján to Triple-A Durham.

The Associated Press contributed to this report.