Sanchez retired the first 13 Iowa batters and went 5 2/3 innings, giving up one run on three hits and one walk. He struck out five.
"Everybody that watched him said he threw good," Royals manager Ned Yost said. "He'll probably have one more rehab start."
Infielder Yuniesky Betancourt, rehabbing from a right ankle sprain, was 2-for-4 with a home run and two RBIs in Omaha's 5-4 loss. In four previous games for Double-A Northwest Arkansas, he was 5-for-15 with a homer and four RBIs.
"He could be back as early as this weekend," Yost said.
If Sanchez gets another rehab start, Yost is leaning toward Vin Mazzaro and Will Smith as the possible starters, respectively, on Sunday against Oakland and on Monday night against Minnesota. Those spots are still in the "to be announced" category. Luis Mendoza is another possibility, but Yost prefers to use him out of the bullpen.