Moonlight was hurt in the Cup quarter-final loss to the United States, exiting at halftime with what Canadian coach Liam Middleton called a "significant rib injury."
"He was in a bad way," Middleton said in an email.
Moonlight did not play in Canada's final game against New Zealand.
The coach said Moonlight is expected to take part in a World Cup qualifying tournament next month in the U.S. although he may have to play through pain.
London was the final stop on the nine-event HSBC World Series. Canada finished ninth in the overall standings.