After the former Chelsea midfielder appeared twice to fire the ball deliberately at Guangzhou players, he was rushed by several opponents. Oscar fell to the ground and a melee broke out.
One player from each side was sent off as the opening of the CSL transfer window was marked in rambunctious style.
The fight erupted just before half-time in Sunday's CSL clash at Guangzhou R&F, where Andre Villas-Boas' SIPG were attempting to keep up the pressure on league leaders Guangzhou Evergrande.
He sparked the confrontation when he lashed the ball twice at R&F players.
More From This Section
The home side's Chen Zhizhao retaliated, pushing the 25- year-old Brazilian to the ground. Then players, coaching staff and substitutes poured off the benches and waded in as Oscar lay face-down on the pitch.
When order was restored after pushing and shoving, R&F's Li Tixiang and Shanghai's Fu Huan were dismissed and three others were booked.
Oscar was unhurt and the fiery encounter finished 1-1 to leave SIPG four points behind reigning champions Guangzhou Evergrande.
"Disrespect the opponent? It is not true. I am a very dedicated player and respect sportsmanship," Sina Sports website quoted him as saying.
Another Brazilian international, the forward Hulk, equalised for Shanghai after being set up by Oscar just before the fisticuffs.
R&F players were incensed that the goal was allowed to stand since Oscar appeared to have been offside before his assist.
Villas-Boas told Shanghai's official social media: "Our goal should be offside and it was unlucky for Guangzhou."
"We are sorry about the infringements during the game and hope the players can adjust their attitude and prepare for the following game," the club said in a statement.