The Orioles designated Rivera for assignment Tuesday.

Rivera was already being used sparingly and his playing time was set to be cut even more with Jordan Westburg (hamstring) back in the fold. The 28-year-old has been outrighted previously, so he has the ability to elect free agency if he clears waivers again.

The Orioles activated Westburg from the 10-day injured list Tuesday.

Westburg is finally ready to rejoin the Orioles' lineup after being sidelined since late April with a left hamstring strain. He looked sharp in eight rehab games with Triple-A Norfolk, going 11-for-28 with a pair of home runs. Westburg will regain his status as the Orioles' everyday third baseman.

Marte (oblique) began hitting from soft tosses in a batting cage Friday, MLB.com reports.

Marte is at the Reds' complex in Goodyear (Ariz.) working his way back from an oblique injury that landed him on the 10-day injured list in late April. The report doesn't give an estimated return date other that sometime in June. Presumably, Marte will go out on a rehab assignment before rejoining Cincinnati.

Bohm went 2-for-5 in Monday's 4-3 extra-innings win over the Cubs.

Although Bohm saw his 10-game hitting streak come to an end on May 30, he's maintained healthy production in the past few weeks. Over his last 20 outings, the 28-year-old infielder is hitting. 305 (25-for-82) with three homers, three doubles, eight RBI and nine runs scored. Bohm has hit either third or fourth in Philadelphia's batting order nine times in his last 12 contests, and he should continue to bat in those positions while Bryce Harper (wrist) is on the injured list.

Urshela (hamstring) is expected to be sent out on a minor-league rehab assignment later in the week, Martin Gallegos of MLB.com reports.

Urshela, who was placed on the 10-day injured list May 23 due to a left hamstring strain, is set to begin a rehab stint with Triple-A Las Vegas. It's been just over two weeks since his last game action, so he should only need a handful of at-bats in the minors before the team feels comfortable activating him.

Karros (undisclosed) has gone 3-for-15 with two RBI, four runs and one stolen base in six games since being activated from Double-A Hartford's 7-day injured list last Tuesday.

Karros is off to a slow start at the dish since returning from an unspecified injury, but he was firing on all cylinders prior to landing on the IL. The 22-year-old is hitting .312 with two home runs and five stolen bases in 28 games for Hartford on the season.

Rengifo is not in the lineup for Monday's game versus the Athletics.

Rengifo is stuck in a season-long slump and has been particularly brutal at the plate lately, going 3-for-30 over his last nine contests. Kevin Newman will hold down third base and bat ninth in Monday's series opener.

Wagaman is not in the Marlins' starting lineup against the Pirates on Monday, Kevin Barral of FishonFirst.com reports.

Wagaman will take a seat after going 0-for-9 with four strikeouts over his last two games. Liam Hicks will start at first base while Heriberto Hernandez serves as the designated hitter and bat ninth.

Triple-A St. Paul placed Fitzgerald on its 7-day injured list Sunday due to a right ankle sprain.

Fitzgerald was hitting just .159 with a .525 OPS in 12 games since he returned to Triple-A from his brief time in the majors. He's hitting .284/.378/.467 with five home runs overall in 47 games at Triple-A.

Machado went 1-for-3 with a solo home run and a walk in a 1-0 win against the Brewers on Sunday.

Machado accounted for the only run by either team with his 425-foot solo blast in the seventh inning. The star third baseman has found his power stroke of late, clubbing three homers over his past four games and seven across his past 16 contests. Machado is also in the midst of a six-game hitting streak during which he's posted a 1.352 OPS with six RBI.