Alexander will start Tuesday's game against the Twins, Matt Kawahara of the Houston Chronicle reports.
The right-hander was called up from Triple-A Sugar Land on Monday and was expected to provide some length out of the bullpen, but he'll instead make a start Tuesday after Lance McCullers (undisclosed) was scratched. Alexander was a decent swingman for Houston last year (3.66 ERA in 14 appearances) but has surrendered 10 earned runs across his two big-league outings this season.