Sonny Bill Williams says "corrupt judges" cost Anthony Mundine victory in the 37-year-old's world title fight with Daniel Geale, while Mundine says he was "ambushed".
Mundine lost a unanimous decision to Geale at the Sydney Entertainment Centre, with two judges scoring the fight 117-111 in Geale's favour and the other 116-112.
Before the verdict was handed down, Mundine was heard to say that he would 'be robbed' if the decision went against him.
When Geale was confirmed as the winner, Mundine stormed out of the ring and into his dressing-room, leaving his softly-spoken opponent to lap up the plaudits.
Mundine later claimed that he was "ambushed".
And Williams, who splits his time between rugby league, rugby union and a part-time boxing career, seemingly agrees the decision was rigged.
Williams posted a picture of himself with fellow boxing rookie Quade Cooper and Mundine on Twitter with the caption "Hanging out with @Anthony_Mundine celebrating a victory.. We don't pay attention to corrupt judges!!"
Cooper, who will have his first professional fight on Williams's undercard next week, retweeted Williams's photo.
Williams later apologised for the tweet, saying his emotions had got the better of him.
As for Mundine, he repeated his claim that he dominated the fight and was robbed of victory.
"I controlled the pace, I stuck him, I hit him more often than he hit me," Mundine said.
"That's what it's about. It's about hitting and not being hit.
"I dominated the fight. I was a ring general. I hit him with cleaner shots (and) I hurt him more.
"But, you know what, I walked into an ambush tonight. It's as simple as that. I thought it was going to be bad but I didn't know it was going to be that bad.
"I thought I was dominant enough to get the victory."
When told of Mundine's displeasure with the decision, the mild-mannered Geale said "it's what you'd expect".
Geale felt he produced the convincing performance he wanted but could have done even better.
"I would have liked to do it that little bit extra," Geale said.
"A lot of people asked me to finish the job and a couple of moments there I had him in some real trouble, I just couldn't find that last little bit.
"He's a great defensive fighter, you can't take anything away from him."
The Tasmanian-born Sydney-based boxer said he wanted to become the number one middleweight in the world.
His American promoter Gary Shaw said Geale would have options to fight next in either Australia or the United States.
"Personally, I'd love to see Daniel back in Australia," Shaw said.
Geale said when he needed to dig a bit deeper he was motivated by some of the taunts Mundine made in the lead-up to the fight.
He said Mundine still had good speed and skill, but just seemed to lack something.