The rookie from Bristol, Va., gave up two runs in 6 2-3 innings, allowing seven hits and striking out two on a career-high 105 pitches in the Texas Rangers' 7-2 victory over the Detroit Tigers.
After giving up two runs in the third, Grimm (3-3) retired 12 of the final 14 batters he faced and exited to a standing ovation. He credited a pep talk from manager Ron Washington after the third inning for his success.
"Wash got me in the dugout and told me to trust my stuff," said the former Virginia High ace. "He kind of tapped me in the face and caught me off guard. Just hearing that he had confidence in me meant a lot."
Grimm, called up from Triple-A Round Rock on April 11, had gotten a no-decision and a couple of wins before hitting a three-game slide.
Elvis Andrus had a career-high five hits, Mitch Moreland homered and Texas roughed up Anibal Sanchez (4-4). Sanchez gave up a season-high six runs in 2 2-3 innings, his shortest start in almost two years. The right-hander yielded nine hits, walked two and struck out two as his ERA jumped from 2.05 to 2.77.
Detroit has lost seven of 11 games and dropped a game behind the Cleveland Indians in the AL Central.