Warner, who injured his left thumb at the Gabba last week, was hit by a Peter Siddle delivery during a net session before play on day two, Cricket Australia reported. Siddle took the field as Warner’s replacement.
“David Warner was hit in the right forearm during this morning’s net session,” a Cricket Australia spokesperson said.
“He has significant bruising which is limiting his ability to field at the moment.”
Warner, who scored a duck in the Australian first innings before the hosts posted 530, is the fourth Australian player to be injured in the MCG nets this week.
On Tuesday, Shane Watson and Mitchell Starc both left training early after being struck in the nets. Watson was hit on the helmet, while Starc edged a ball onto the inside of his knee.
The following morning, Shaun Marsh was struck on the left thumb and required treatment before he continued his session.
The problems in the MCG nets come after the Indian pair of Shikhar Dhawan and Virat Kohli got hit in the Gabba nets before play on the fourth day of the second Test and subsequently the visitors complained about the practice pitches on offer.