The 20-year-old took a nasty kick to the back of the leg from James McArthur in the first half - which controversially only warranted a yellow card from Mike Dean - and had to be replaced by Albert Sambi Lokonga at half time.
Arsenal boss Mikel Arteta has not been able to offer a positive update on Saka's injury, and the Arsenal boss also blasted the decision not to brandish a red card to McArthur for his challenge.
Speaking to Sky Sports News, Arteta said: "He was very sore in the area. When I look at the action I cannot understand how the player [McArthur] can continue to play."
Arsenal had to rely on Alexandre Lacazette to rescue a point with virtually the last kick of the game at the Emirates, with Christian Benteke and Odsonne Edouard netting after Pierre-Emerick Aubameyang's opener.
The last-gasp draw leaves Arsenal unbeaten in five Premier League matches and sitting 12th in the rankings after eight matches. body check tags ::