The Nationals need a starter for that day because they don't want right-hander Jordan Zimmermann to pitch on short rest. Zimmermann pitched Wednesday on seven days' rest because of a rain postponement the previous day.
Wang helped himself during a 7-6 loss to the Dodgers on Wednesday by not allowing a run in 2 1/3 innings. It was Wang's first Major League appearance since June 30.
He did get off to a slow start in the game, however, throwing a wild pitch that allowed Shane Victorino to score and make it a 5-0 game. With two outs and Wang on the mound, Matt Kemp ended up scoring the sixth run for the Dodgers on a fielder's choice by Ramirez.
"I like the way Chien-Ming Wang threw [Wednesday]," Johnson said. "He had good sink. [I considered Craig] Stammen, but he has been invaluable [as a reliever]. If I start him, I kind of lose him two or three days before and probably two or three days after. I don't want to do that at this point. Chien-Ming, I like who he is, I like what he is all about. I like his competiveness. He has been in big games and, to me, all of these are big games. I think he will do a good job on Sunday."
Wang had two stints on the disabled list this year because of hamstring and hip injuries. After he recovered from the hip injury, Wang spent time rehabbing in the Minor Leagues. During his Major League stint, Wang is 2-3 with a 6.92 ERA in eight games.