Tami Chappell/Reuters

Oft-injured pitcher Chien-Ming Wang will start Sunday against the Milwaukee Brewers, filling in as a spot starter, Nationals Manager Davey Johnson said. After Wang tossed 2 1/3 innings Wednesday night, Johnson saw enough improvement in his delivery to give him the Sunday start.

Because of Tuesday’s rainout and Wednesday’s doubleheader, starter Jordan Zimmermann’s schedule was pushed back a day. He started the first game of the doubleheader, and if he pitched in his turn on the schedule, he would start Sunday on just three days’ rest. Johnson didn’t want to pitch any of his starter’s on shorter rest than normal, so he weighed his options for a few days and decided on Wang, who induced six groundballs in relief of John Lannan Wednesday.

“He was a lot better,” Johnson said. “You saw the groundballs. They got some good left-handed hitters, and some of them hit the ball pretty hard. Milwaukee doesn’t have the luxury of those kind of left-handed hitters; they’re predominately a right-hand hitting club. He also threw a couple good curveballs. I like who he is and his competitiveness, and I don’t have any qualms at all.”

To start Sunday, Johnson considered Wang and long reliever Craig Stammen, a former starter. But Johnson felt Stammen was too valuable in his role, and if he used him as a starter, he would be unavailable to pitch for at least two days before and after Sunday.

In spring training, Wang was slated to be the Nationals’ fifth starter until he tore his hamstring while covering first base. After he returned to the Nationals in late May as a reliever, he was inserted in to the starting rotation over a then-struggling Ross Detwiler.

But Wang was ineffective and put back into the bullpen. He later suffered a recurring hip injury that landed him on the disabled list and prevented him, the Nationals believed, from getting on top of the ball to get his trademark sink. Wang has made just four starts for the Nationals this season but has started 15 times in minor league rehab assignments. He has a 6.92 ERA across four starts and for relief appearances for the Nationals this season.

“Overall, I feel okay and then the last few months I make adjustments and then pitching coach [Steve McCatty] was kind of helping me during the last two bullpen sessions,” Wang said after Wednesday’s game. “So I think I’m trying to make myself better in the future …  I think my sinker was low today and then the angle was pretty good.”

One evaluator who watched Wang pitch last night said he looked much better than earlier in the season. “He had more hair on his fastball,” he said.

At first, Johnson was worried about Wang’s stamina. But after Wednesday’s performance, he felt the right-hander, who won 19 games for the New York Yankees in both 2006 and 2007, had enough to start a game. “He’s awful strong and can throw a lot of pitches if he doesn’t try to overthrow,” he said.