Bulls point guard Rajon Rondo said he will not return for Game 5 of Chicago's first-round series against the Celtics on Wednesday night despite making an attempt to return early from his fractured right thumb and ailing right wrist.

He also revealed Wednesday that what has been described as an injury to his wrist is actually a torn ligament. Nonetheless, Rondo has switched from a cast to a soft splint. He participated in most of practice Tuesday while protecting the injured hand.

Sources told ESPN that Rondo held a private workout Tuesday night in hopes of getting a better read on how feasible a comeback would be after missing only two games.

He said Wednesday that it's too early to say whether he could play in Game 6 on Friday.

Bulls point guard Rajon Rondo missed Games 3 and 4 with a fractured right thumb and ailing right wrist. Kent Smith/NBAE via Getty Images

‎"He wants to play bad," one source close to Rondo said Tuesday night. "As of right now, it's still tender and he's erring on the side of waiting until Game 6."

Rondo, 31, suffered the injury in Game 2 and was expected to be in a hard cast for at least seven to 10 days. In the wake of the Bulls' two home defeats that evened the series at 2-2, Rondo showed up for practice Monday without the cast.

Coach Fred Hoiberg has described Rondo's return in this round as a "long shot" but also acknowledged that Rondo was likely to try to do anything he could to come back after eighth-seeded Chicago squandered a 2-0 series lead.

"This is honestly the first time he's touched a basketball with that right hand," Hoiberg said of Tuesday's jumpers in front of the media. "We'll see. We'll see how it goes. He's going to continue to condition and do everything that he can. He was in the weight room yesterday getting a good session in there. It was his first time back in the weight room. He's just getting this whole process started."

After winning the first two games of the series in Boston, Chicago looked discombobulated without Rondo in Games 3 and 4. Backup point guards Jerian Grant and Michael Carter-Williams are shooting a combined 6-for-28 in the series and have turned the ball over nine times in the past two games.

Hoiberg is so desperate for a spark at point guard that he said he's planning to start little-used Isaiah Canaan in Game 5. It would be Canaan's first start of the season.

Rondo's return would provide a big morale boost for a Bulls team that was rocked by its two home losses. Rondo averaged 11.5 points, 10 assists, 8.5 rebounds and 3.5 steals in Chicago's two road victories to open the series.

"Obviously, that's huge," Bulls All-Star swingman Jimmy Butler said of Rondo's potential return. "We want that guy back, but I don't know if it will happen, if it won't happen; I can't tell you that.

"He's still out here shooting shots with his left hand from the corner. He just shot that one right-handed, actually, air-balled it. But we love him. He's our floor general out there. He knows everything. He knows every matchup, every position, and he's still helping from the bench. We really want him helping out there from the floor."‎

ESPN's Marc Stein, Marc Spears and Nick Friedell contributed to this report.

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