Two starts ago, Cincinnati's Alfredo Simon didn't fool anyone in suffering his worst loss of the season.
In his last outing, a new pitch helped the right-hander baffle hitters as he put together one of the best starts of his career.
With Joey Votto and Jay Bruce still unlikely to play, the scuffling Reds turn to Simon to shut down a Washington team coming off its highest-scoring game in nearly four weeks in Wednesday's series finale at Nationals Park.
Votto missed his fifth consecutive game Tuesday due to strained left quadriceps, and manager Bryan Price expects him to return to the lineup after Thursday's off day. Bruce is eligible to come the disabled list on Wednesday, but it's possible he may begin a rehab assignment.
Cincinnati (20-24) hasn't done much offensively without two of its top hitters, averaging 2.9 runs while batting .213 in its last 13 games.
Brandon Phillips is hitting .192 with two RBIs in the last six games for the Reds, who are batting .120 with runners in scoring position in their last 11 contests.
Washington (24-21) broke out offensively in Tuesday's 9-4 win, scoring its most runs since an 11-1 victory over San Diego on April 25. Denard Span, who came in batting .239, finished 5 for 5 with two doubles, two runs, two RBIs and a stolen base.
Nationals manager Matt Williams hopes that performance can help Span get his season turned around.
''Looking back at last year, he started a really good streak in the second half,'' Williams said, ''so certainly it can get him going.''
While building on Tuesday's showing seems like a tall order against Simon (5-2, 2.45 ERA), the Nationals may not be too intimidated after roughing up Johnny Cueto for eight runs - six earned - in 5 1-3 innings. Cueto entered with a major league-best 1.25 ERA.
Simon entered his start against Colorado on May 10 with a 1.99 ERA, but it shot up nearly a full run after he was tagged for five runs in three innings in an 11-2 loss. He served up three homers and didn't notch a strikeout.
He regrouped six days later in Philadelphia, allowing five hits while striking out a season-best eight in 7 2-3 innings of a 3-0 win. He retired 13 of the last 15 batters he faced, and caught hitters off guard by mixing in couple of pitches clocked in the low 70s.
''I don't know what he was throwing half the time,'' catcher Devin Mesoraco said. ''I was just catching it and throwing it back.''
Simon will be making his first start against the Nationals after posting a 2.57 ERA in 10 relief appearances.
Washington gives the ball to Tanner Roark (3-1, 3.65), who is set to make his first appearance against the Reds.
Excluding a loss in Philadelphia on May 3, when he yielded seven runs in four-plus innings, Roark has a 0.95 ERA in his other four outings since April 21. The right-hander gave up two runs and four hits in five innings in Friday's 5-2 win over the New York Mets.
He is 2-0 with a 0.87 ERA in three home starts, while Simon has a 0.99 ERA in winning all four road starts.