New Zealand team management said it was too early to draw firm conclusions about the injury to paceman Kyle Mills, who limped off while bowling in Sunday's match against Canada.
Mills, who opened the bowling in his team's 97-run win, left the field after only 2.4 overs of his spell, in which time he took 2-2.
New Zealand media manager Ellery Tappin said no firm conclusions could yet be drawn.
"It was a strain in the quadriceps of his left leg. He will be kept under 48-hour observation," he said.
Captain Daniel Vettori missed Sunday's match due to a knee injury but is expected to return to the side for Friday's game against Sri Lanka.
Sunday's win gave New Zealand a place in the quarter-finals.
