Cleveland Indians outfielder Kosuke Fukudome hit a line shot back up the middle in the second inning of the White Sox's eventual 4-2 defeat, giving Humber barely enough time to flinch. Humber turned his head slightly and raised his glove but couldn't slow down the ball.
"I saw it, but a little late," Humber said. "I wasn't as quick as I thought. But I was very fortunate and one thing I would like to say is that my wife was here, so obviously it was upsetting for her. But she told me the fans were very supportive and had a lot of kind things to say to her, so I appreciate that."
As the ball rebounded off Humber's forehead, it carried across the third-base foul line near home plate, where catcher Tyler Flowers retrieved it.
Humber went straight down on his back after getting hit, but got to his feet in short order. He was removed from the game immediately, but was talking to White Sox trainer Herm Schneider as he left the field.
"I saw him kind of collapse on that, so I wasn't sure if it had knocked him out or something," Flowers said. "The second thought was the ball was coming back my way and the play wasn't over yet. But obviously right after that was to get out there and make sure he was all right."
Sporting a knot over his eye after the game, Humber said he had only a mild headache that was managed with some over-the-counter pain relievers. He was given a list of precautions before he was sent home and will be re-evaluated Friday.
"That's a God thing," Humber said. "There's a hand of protection around me. And I'm definitely thankful it wasn't a lot worse and that I'm OK."
Manager Ozzie Guillen said he still didn't know if Humber would make his next start, which is lined up for Wednesday against the Angels on the West Coast.
"I guess it could have been an ugly night; it was just one game we just lost," Guillen said. "Thank God nothing happened to this kid."
Humber was also hit in the face by a comebacker last season while pitching in the Royals organization at Triple-A Omaha. A liner from Luis Cruz on July 10 hit him on the right side of his mouth. That injury required 18 stitches to close.
"Same thing, it could have been worse," Humber said. "I'm just very thankful. I've got to do some drills to get my reflexes faster or quit getting line drives up the middle."
Humber, in his first season with the White Sox, was a revelation in the first half when he was 8-5 with a 3.10 ERA. He hasn't been nearly as sharp since the break, going 0-3 with a 6.35 ERA in four starts before his outing Thursday.
In 20 starts plus one relief appearance before Thursday, Humber was 8-8 with a 3.67 ERA. He was replaced by rookie Zach Stewart, who was making his fourth appearance of the season.
Doug Padilla covers the White Sox for ESPNChicago.com.