Braves closer Rafael Soriano will have an MRI and other tests done on his right elbow Wednesday to determine what is causing his lingering soreness.

The right-hander has been on the disabled list for a month and had to cut short a bullpen session Tuesday after the soreness flared up again in his pitching elbow.

"We're going to see if we can get to the bottom of it," Braves general manager Frank Wren said. "It just hasn't seemed to improve much."

Soriano will have tests and be examined by a Braves doctor. Wren said Soriano will have the same battery of tests that was administered in January before the team signed him to a two-year, $9 million contract.

Soriano had soreness almost immediately after he began throwing in spring training and ended up missing half of the Grapefruit League schedule. He made four appearances this season before the soreness cropped up again and he was placed on the 15-day DL.

Since his injury and a subsequent elbow injury to setup man Peter Moylan, the Braves have scrambled to fill in for what were their top two relievers in 2007. Rookie Manny Acosta has been the primary closer since Soriano went down, though Acosta has only two saves in two opportunities.

In his first season with the Braves in 2007, Soriano went 3-3 with a 3.00 ERA and career-highs of 72 strikeouts, 71 appearances and 70 innings. He converted nine of 12 saves as the backup to closer Bob Wickman, who was released in late August.

Wren said the hard-throwing Dominican passed a physical in Atlanta before signing his contract. He got a $500,000 signing bonus and salaries of $2.4 million in 2008 and $6.1 million in 2009.

Wren said he thinks the Braves can get by with the arms they have available in the bullpen and the expected infusion in coming weeks.

Left-hander Mike Gonzalez had what the Braves described as a minor setback this week in his recovery from "Tommy John" elbow-ligament surgery, but is still expected back near the end of the month.

John Smoltz plans to move to the bullpen after returning from the disabled list, though it's not certain if that will be in a few weeks or take longer. The veteran starter went on the DL last week with an inflamed rotator cuff and severely inflamed biceps tendon.

Moylan with have elbow surgery Thursday and is expected to be out at least 12 months.