A groundsman appeared to be spraying a green substance onto the dry brown patches that scarred the pitch at the Arena Amazonia on Thursday to make it look more ordinary.
International players' union FIFPro argued FIFA was putting players' safety at risk by allowing them to play on such a pitch, but England are relaxed about the whole situation.
Press Association Sport understands the England management received a report on the Manaus pitch from the Sports Turf Research Institute (STRI).
The STRI said that, while the pitch may not look aesthetically pleasing, it thinks the surface will play fine when England face Italy in their first Group D match.
For that reason, England scrapped their plan to send a member of the backroom staff to have a look at the pitch.
FIFA did not respond to questions about dying the grass, but it did admit it had conducted "treatment" on the surface.
England striker Wayne Rooney is not fazed about the prospect of playing on such a dry pitch.
"We're not sure, but I think at the end of the day it's the same for ourselves and Italy so we'll both have to deal with that," he said.
His words were echoed by England goalkeeper Joe Hart, who said: "We've both got to play on it, whatever it is. I think they've worked day and night over here to make it the best it can be.
"We've got to appreciate we're playing in the jungle, so we'll take anything."
England and Italy will hold hour-long training sessions on the pitch on Friday night.
England were greeted by temperatures of 33 degrees when they touched down in Manaus on Thursday.
All the squad travelled to the jungle city, which is located around 1,000 miles up the Amazon river.
Danny Welbeck looks to be in contention for a starting place against the Azzurri after he took part in a light gym session along with his team-mates despite a recent thigh injury.
Alex Oxlade-Chamberlain, who sustained a knee injury against Ecuador last week, also made the three-and-a-half-hour flight to Manaus, although he is unlikely to play against the Italians, who land on Friday.
- Sports & Recreation