Gordon sustained the injury just before halftime of the Rockets' 137-112 win Tuesday at the ESPN Wide World of Sports complex inside Walt Disney World Resort.
Gordon took a dribble before he stepped on the foot of the Celtics' Vincent Poirier with 1:08 left to play in the second quarter. Gordon then collapsed on the court and grimaced as he held his left ankle. He then was tended to by the Rockets' medical staff before his teammates helped him off the floor.
Rockets coach Mike D'Antoni said Gordon got a negative result on an x-ray of the ankle after the game.
"It hurts a little bit, but didn't really swell," D'Antoni told reporters. "So we won't know the extent of it until [Wednesday]. He is going to be out for a few days."
Ben McLemore replaced Gordon in the lineup after the injury, but D'Antoni said "we'll see" when asked about Gordon's replacement going forward. His absence of a "few days" will sideline him for practice and puts him in danger of a multiple-game absence.
Sources told ESPN Gordon could miss up to two weeks due to the injury. The Rockets resume their 2019-2020 regular season campaign with a game against the Dallas Mavericks at 9 p.m. EDT Friday in Orlando. Houston's second game in Orlando will be Sunday against the Milwaukee Bucks.
The Rockets are in sixth-place in the Western Conference standings, with a 1.5-game lead on the seventh-place Dallas Mavericks. The Rockets are now in position to face the Denver Nuggets in the first round of the playoffs, but a slip to the No. 7 or No. 8 seed could force them into a first-round matchup against the Los Angeles Clippers or Los Angeles Lakers.
Gordon, 31, is averaging 14.5 points, 1.9 rebounds and 1.5 assists this season. The 12-year veteran scored nine points and had two rebounds and an assists in 15 minutes Tuesday in Orlando.