Pelfrey, who gave up nine runs over five innings in a Minor League game five days earlier, surrendered four runs on seven hits over five innings Sunday in his next-to-last spring tuneup.
"I thought I was OK. I didn't think I was great," Pelfrey said. "I thought I really struggled to get in on lefties. A lot of balls leaked back over. I especially got hurt by the Castro ball."
Pelfrey's next assignment will depend on whether he or Anibal Sanchez pitches the second game of the regular season next Wednesday at Miami. If it's Pelfrey, he'll pitch Friday against the Rays at Joker Marchant Stadium. If not, he'll likely pitch on the Minor League side in preparation for a spot further down in Detroit's rotation.
Bruce Rondon, vying for a role in a Tigers bullpen suddenly wide open with injuries, left fastballs up and paid for them Sunday. Reed hit a two-run home run to right-center in the seventh, followed a couple of batters later by Singleton's solo homer.
Feldman, pitching a day later than scheduled thanks to a Saturday rainout, tossed four innings of one-run ball, his lone damage coming in a three-hit second inning. Shortstop prospect Alex Bregman kept it at that with a diving catch up the middle on Anthony Gose's liner.
Gregerson, making his first Major League appearance this spring, followed Feldman by striking out the Tigers in order on nine fifth-inning pitches to James McCann, Gose and Ian Kinsler.
McCann, catching all nine innings for the first time Sunday as he begins to build innings following his week-long absence with the flu, hit a one-hopper to the left-field berm for a ground-rule double in the second inning before hitting the berm on the fly for a two-run homer off Fiers in the seventh.
Designated hitter Jarrod Saltalamacchia and third baseman Casey McGehee each had 2-for-4 days at the plate for Detroit, scoring a run apiece as well.
Up next for the Astros: The Astros, who have spent the last two days playing split-squad games in Mexico City and Florida, will reunite closer to their Kissimmee home on Monday, playing a night game against the Braves at 5:05 p.m. CT at Disney's Wide World of Sports complex. Right-hander Doug Fister will take the mound for Houston, making his fifth spring start. Wandy Rodriguez, battling for the last spot in the rotation, will also pitch in the game in relief. The Braves will counter with former Astros farmhand Mike Foltynewicz.
Up next for the Tigers: Buck Farmer will make one more play for a spot on the Tigers' pitching staff when he gets the start Monday night against the Yankees in a 6:35 p.m. ET game in Tampa. Farmer is competing with Shane Greene and Matt Boyd for the fifth spot in the Tigers' rotation, but stands a stronger chance of cracking the bullpen. Former Tigers prospect Luis Cessa, traded to New York in the Justin Wilson trade last December, is scheduled to start for the Yankees.