Sources: Warriors face Sunday night deadline on Gary Payton trade

The Golden State Warriors are under a 9:30 p.m. ET deadline on Sunday night to make a decision on squashing a four-team trade with Portland, Atlanta and Detroit because of issues surrounding  Gary Payton II's abdomen injury, sources told ESPN on Saturday.

After Payton arrived in a Thursday trade with the Portland Trail Blazers, a physical revealed that he would be out for a significant part of the remaining season, sources said. The Warriors have shared with the league office that they believe Portland withheld relevant medical information prior to agreeing on the trade, sources said.

The trade can't be amended or changed because the league's trade deadline passed on Thursday at 3 p.m. ET.

The NBA could punish Portland with a fine and loss of draft picks if an investigation were to discover "a failure to disclose relevant information" on Payton's abdominal injury that required offseason surgery and had him miss the first 35 games of the season.

The Warriors believe they should've been told that Payton had been using Toradol shots to alleviate pain, sources said, something that's more typically done for players in the playoffs rather than the regular season.

The Warriors sent former No. 2 overall pick James Wiseman to the Pistons, who sent forward Saddiq Bey to the Hawks and Kevin Knox to the Blazers. The Warriors sent five second-round picks -- including two via Atlanta -- to the Blazers in the deal.

The rest of the players have passed physicals and joined new teams and are now waiting to find out if they'll get to stay or have to return to their original teams. Blowing up the deal will add $35 million to the Warriors' luxury tax bill this season.

Blazers general manager Joe Cronin told reporters on Friday in Portland that the Blazers were "confident" Payton was healthy.

"Player safety is super important to us, it's a super important thing around the league," Cronin said. "We were playing him, he was playing, and he had been cleared and we were confident that he was healthy when he was playing. We would not have brought him back if we thought he wasn't healthy or if he was at risk. So you trust that we did the right thing and trust that our process was correct."

Payton, 30, signed a free agent deal with the Blazers after breaking out with the Warriors a year ago. Golden State reacquired Payton believing that he would improve its perimeter defense.

Payton averaged 4.1 points in 17 minutes. He has two years and $18 million left on his contract.

ESPN's Bobby Marks contributed to this report.