After hobbling in pain, Carpenter was briefly checked by manager Aaron Boone but finished the at-bat and struck out swinging on the next pitch. He said he knew something was wrong but thought he could finish the at-bat and drive in a run.
"When I went to swing on the next pitch, as soon as I started to plant and rotate on that back foot, my lower body like gave out and I wasn't able to," Carpenter explained. "Thankfully, probably the best thing that happened was to swing and miss -- because if I hit it and had to run, I might have made it worse. But I knew it wasn't good."
Carpenter, wearing a protective boot in the Yankees' clubhouse after the game, said he is hopeful he might only miss a month. But a timeline won't be determined until he sees a foot specialist.
"I don't want to say a number because I just don't know, but I'm holding out hope that it'll be a situation where I could come back in the middle of September and can contribute towards a stretch run,'' Carpenter said. "So we'll see. I mean, that's my mindset is that I'll be back.''
Boone said he was immediately aware something was wrong and realized a change was needed when he checked on Carpenter in the clubhouse between innings.
"I knew he got it good. That's why I went out there initially,'' Boone said. "And I was just like, the way he was moving, I'm like, this isn't good."
"I have no doubt in my mind that [Carpenter] is going to still make an impact on this team even while he's hurt,'' said Yankees starter Jameson Taillon, who threw seven innings to get the win. "He's come in here right away and made an impact on a lot of people. He's not afraid to talk pitching with the pitchers. He's not afraid to give honest feedback. He's one of the best guys that I've been around and played with, so I wouldn't be surprised if he finds his way back and makes an impact.''
A front-runner for American League Comeback Player of the Year, Carpenter is batting .305 with 15 home runs and 37 RBIs in just 128 at-bats for New York this season, and he had reached base in 27 of his 35 starts. Last month, he batted .356 in 73 at-bats.
All this came after hitting seven home runs in 418 plate appearances over the previous two seasons.
The Texas native signed with the Yankees in May after he was released by the Rangers, for whom he spent the first month and a half of the season toiling at Triple-A.
Since debuting with the Yankees on May 26, Carpenter has a .727 slugging percentage, the best in MLB during that span (minimum of 100 plate appearances). New York has averaged 6.5 runs per game with Carpenter in the lineup and 4.8 runs without him.
"He's definitely going to be missed for however long it's going to be, but we're hoping that we get some good news and that it's not going to be season-ending," Yankees third baseman Josh Donaldson said.
Carpenter entered Monday night's game following an emotional series against the St. Louis Cardinals, the team with which he spent the first 11 years of his career. Carpenter received a lengthy standing ovation prior to his first at-bat and went 2-for-12 in the series at St. Louis.
His is the latest significant injury for the Yankees. All-Star slugger Giancarlo Stanton and pitchers Luis Severino, Michael King and Miguel Castro all went down hurt last month, and they haven't returned.
King will miss the rest of the season with a broken right elbow, while Severino (right lat strain) and Castro (right shoulder strain) are also on the 60-day injured list. Stanton is on the 10-day IL, retroactive to July 24, because of left Achilles tendinitis.
New York has the best record in the AL at 71-39 and leads the AL East by 10½ games.
ESPN Stats & Information and The Associated Press contributed to this report.