Previously playing left field for the Nationals, Willingham will make his first start in right field tomorrow.
"He's been working there the last three or four days," manager Manny Acta said. "He'll have to take some more balls, to get used to the angle of the ball. He's a decent athlete; I think he can make the adjustment."
Acta cited the desire to keep Adam Dunn in left field as a reason for Willingham's move across the outfield.
When Willingham was healthy and in the lineup as a left fielder, Dunn played right field. But when Austin Kearns started instead of Willingham, Dunn played left field so Kearns could play in right.
"We want to keep Adam in one spot," Acta said. "We really appreciate his willingness to be moving all over the place. But I think for his own good, we're going to keep him in left field instead of moving him all over the place."
Acta hinted that Willingham and Kearns would platoon in right field until one player ran away from the other in terms of production.
Kearns has struggled mightily the past month. He has no RBIs in his past 21 games, hitting .193 with one extra-base hit during that span.
Meanwhile, Willingham was batting .252 with nine home runs this season before being sidelined with the infection.
"We'll see how he is physically, then we'll make a decision about his playability," Acta said. "First he has to go out there -- he hasn't played in a week. Once he shows that he can swing the bat the way he was swinging it, he'll play more often than not."
Willingham is available to pinch-hit in Tuesday's game. He told Acta that he was at about 90 percent strength.
Mark Selig is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.