An MRI taken after Thursday's game confirmed the strain, which was announced by general manager Brian Cashman in a Yankee Stadium press conference on Friday afternoon. Jeter suffered the injury running to first base in his third at-bat of the season.
"We are going to not play him through the weekend and then we have the four days from the All-Star break," Cashman said. "We're going to evaluate it sometime after that. It could resolve after that time frame, it could take more time."
Cashman said that he could not rule out that the 39-year-old Jeter will eventually need to go back on the DL because of the strain. New York returns to action from the All-Star break on July 19 against the Red Sox at Fenway Park.
Jeter's injury is not out of the ordinary for the Yankees, who have had more than their share of not only injuries this season, but also re-injuries to players like Jeter, Curtis Granderson and Mark Teixeira.
"This group has been pretty good about moving on," Yankees manager Joe Girardi said. "You have to move on for a few days. We'll evaluate it as we go on day by day."
Serving as the Yankees' designated hitter in their 8-4 win over the Royals, Jeter went 1-for-4 with a run scored and an RBI groundout. He logged an infield hit on a ground ball to third base in his first at-bat of the season.
The Yankees captain showed no ill effects from his twice-fractured left ankle in his first at-bat, also running smoothly from first base to third base on a Robinson Cano single.
After his third at-bat, a ground ball to second base, Jeter told head athletic trainer Steve Donohue that he felt something like a cramp in his quadriceps. After grounding out in his fourth at-bat of the afternoon, Jeter was replaced by Brett Gardner as an eighth-inning pinch-hitter.
"Derek doesn't usually say anything," Cashman said. "When he said something, he said, 'Cramp.' A cramp for Derek is something more than a cramp, and the MRI confirmed that."
The Yankees' original plan had been that Jeter was to DH on Thursday at Triple-A Scranton/Wilkes-Barre and, if healthy, would have played shortstop for the Yankees on Friday against the Twins.
Injuries to Brett Gardner and Travis Hafner on Wednesday prompted Cashman to accelerate Jeter's timetable by a day, rushing him to the Bronx to DH against Kansas City.
Cashman said that he was "caught off guard" when Donohue called him during the game, saying that Jeter would need to be removed, and Cashman allowed that it is "possible" that rushing Jeter to New York had something to do with the quad strain.
"I guess it's all open for questions," Cashman said. "It was my call to move him up based on what occurred in our game, and I thought it was a safe harbor because it was a DH situation."
Cashman said that he had heard from longtime Yankees executive Gene Michael and others that Jeter seemed to be moving well at Triple-A, suggesting there was no reason to fear an injury.
"It's not something that entered my mind in any way, that he could actually blow a tire running the bases or stretching things out," Cashman said. "He could do it down there as well as he could do it up here."
Jeter missed the Yankees' first 91 games of the season while recovering from left ankle surgery, as well as a new fracture suffered during Spring Training. Despite this most recent injury in what he has called his most frustrating season, Girardi characterized Jeter's mood as "feisty."
"He wants to play tonight. Normal Derek Jeter stuff," Girardi said. "His frame of mind is good. He wants to give it a shot after these seven days and see where he's at -- which is, to me, normal Derek Jeter."