"When I turned first base, it felt like a 'catch' in Spring Training," he said.
DeJesus missed time in Spring Training with a similar injury, but it was to the other hamstring.
Manager Buddy Bell said he didn't know how long DeJesus might be out. However, the Royals usually are cautious about such injuries, which could mean that DeJesus also will sit out Sunday and see how he feels after Monday's open date.
DeJesus is hitting .250 (3-for-12) with two doubles and a triple in the first three games.
His injury gives a shot to Shane Costa, who won the backup outfield job over Aaron Guiel this spring. Costa batted .310 in camp and was 1-for-3 in the regular season before Saturday's start.
Mike Sweeney, who still wears a protective pad on his left elbow from previous encounters of the wrong kind, was drilled near that area by White Sox pitcher Javier Vazquez in the sixth inning on Saturday.
He stayed in the game.
"It's a little bit stiff. But [trainers] Nick Swartz and Frank Kyte -- and this is the luxury of being the DH -- were able give me treatment. Without them, I probably wouldn't have been in there and Matt Stairs would've probably hit the game-winning home run," Sweeney said.
Sweeney, in his next at-bat, hit a two-run shot that gave the Royals a 4-3 victory.
Buy a vowel: The Royals might have checked with "Wheel of Fortune" but turned to Stats Inc. instead.
Has any right side of the infield ever had longer last names than second baseman Mark Grudzielanek and first baseman Doug Mientkiewicz?
Their combined 24 letters (12 in each name) surpasses the 22-letter combination of the 1954 St. Louis Cardinals with second baseman Red Schoendienst and first baseman Joe Cunningham.
Stats based the research on players with the most games played at first base and second base in a given season.
If Tony Graffanino would be playing third base or shortstop some day, the Royals could pull off a 34-letter double play: Graffanino to Grudzielanek to Mientkiewicz.
Doesn't exactly have the ring of Tinker to Evers to Chance, does it?
On a roll: Grudzielanek doubled in the first inning Saturday after breaking an 0-for-9 getaway with two hits in Friday night's 11-7 win.
"I guess, from the papers, it was my worst start ever. I don't know about that," he said.
Late in Friday night's game, Grudzielanek was unable to score from third base after Mike Sweeney's liner was snared in right field.
"It was just a bad move," he said. "I hadn't been out there very often."
But he has now. Grudzielanek, who singled ahead of Sweeney's game-winning homer, is 5-for-8 against the White Sox after going hitless in two losses to the Tigers.
Up next: The Royals wrap up the three-game series against the White Sox at 1:10 p.m. CT on Sunday. Scott Elarton (0-1, 3.18 ERA) is matched against Sox left-hander Mark Buehrle (0-0, 6.75 ERA).