The Boston Red Sox believed they were headed to extra innings on a frigid night at U.S. Cellular Field.
Tied at one against the White Sox in the bottom of the ninth inning, Boston reliever Chris Capuano appeared to strike out Marcus Semien on a check swing on a 2-2 count to end the inning.
Instead, it was ruled a ball following an appeal to third base umpire Doug Eddings, and it cost the Red Sox one pitch later.
Semien hit the next pitch to Boston shortstop Xander Bogaerts, whose one-hopped throw to first baseman Mike Carp wasn't handled cleanly.
Alexei Ramirez, who reached on a one-out single against reliever Burke Badenhop and advanced to second on Capuano's walk of Adam Eaton, ran on the 3-2 pitch and never stopped.
Bogaerts' throwing error allowed Ramirez to score easily to give the White Sox a 2-1 walk-off win.
"It's cold weather, but that's no excuse for that play," Bogaerts said. "That's a ball I should've thrown right at the chest to him."
Boston manager John Farrell thought Capuano had struck out Semien.
"The check swing from the open side clearly looked like - given some of the other check swings that were called here tonight - it was more extensive than some other ones," Farrell said. "But we don't get the call."
Badenhop (0-2) took the loss, and White Sox reliever Daniel Webb (1-0) got one out in the ninth for the victory, the first of his major league career.
"No, I didn't think I swung," Semien said. "I looked back and saw how A.J. (Pierzynski) caught it and made it look like a pretty good pitch. I think they were mad about it not being a strike. ... I am glad I ran down to first hard and good things happened."
Daniel Nava homered for Boston, which has lost three straight. Twelve of the Red Sox's 15 runs in their past six games have come via the home run. Nava's homer in the fourth off White Sox starter Erik Johnson tied the game at one.
Boston, which has averaged only 3.5 runs per game, fourth fewest in the American League, watched its cleanup hitter leave the game with an injury.
First baseman Mike Napoli left in the top of the ninth inning after dislocating his left ring finger sliding into second base on Donnie Veal's wild pitch. X-rays were negative, and Farrell said Napoli is day to day.
"I really don't do it often," Napoli said of sliding head first. "But on a play like that when I don't know what kind of throw or what's going to happen and I see Alexei coming across. It's my first instinct to try and get to the bag as quick as possible."
The temperature at first pitch was 40 degrees. All the players except for Johnson and Eaton wore long sleeves under their jerseys and the upper deck was closed because of ice on the ramps.
Adam Dunn homered for the White Sox, who have won four of their past five games.
Red Sox starter Jake Peavy allowed one run and three hits in six innings on 113 pitches against his former team in his third straight no-decision. He struck out eight and walked four.
Johnson pitched 6 2-3 innings and struck out a career-high nine in his eighth career start. The 24-year old right-hander allowed one run and three hits with two walks.
Before the game, the White Sox paid tribute to the one-year anniversary of the Boston Marathon bombings. The White Sox players wore "Boston Strong" T-shirts during pregame and there was a video montage along with a moment of silence.
In the second inning, White Sox manager Robin Ventura challenged a call by first base umpire Cory Blaser. Ventura challenged that Napoli's foot was off the base when he fielded Bogaerts' throw to get Jose Abreu. The replay was ruled inconclusive so Blaser's call was upheld.
Dunn followed with his third homer of the season.
Ramirez extended his hitting streak to 14 games with his single in the ninth.
David Ortiz was called out on strikes in the fourth inning on an appeal to Eddings. Ortiz was livid after Eddings ruled that the slugger didn't check his swing. Farrell had to intervene to prevent Ortiz from being thrown out of the game.
With two outs, Nava tied the game with a solo shot to right. It was his second homer of the season.