CHICAGO -- It's not unusual for Isaiah Thomas to exult on the court, but this was different. It seemed as though many of the emotions trapped inside him over the past two weeks came spilling out Friday night.

Midway through the third quarter, as the Boston Celtics were racing away from the Chicago Bulls in Game 6 of their Eastern Conference first-round series, Thomas watched teammate Al Horford slip a screen and run free to the rim. Thomas scooped a lob toward Horford, who threw down an emphatic two-handed slam that put Boston in front by 22.

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Inside a hushed United Center, Thomas flexed his arms in a familiar pose -- fists clenched and arms by his sides -- and then screamed. Only he kept screaming. It felt as if he screamed for the entire duration of the TV timeout as teammates rushed to revel with him.

"He wanted it. We all wanted it," teammate Jae Crowder said after Boston's series-clinching 105-83 triumph that was Boston's fourth consecutive victory after falling into an 0-2 hole in the series.

"Just emotions coming from the game, how big we put the game up there, how big it was, and how much people wanted it as a group," Crowder added. "He was just letting it all out, I guess."

Thirteen days ago, on the eve of the playoffs, Thomas' younger sister Chyna Thomas was killed in a single-vehicle accident near their native Tacoma, Washington. Distraught with grief, Thomas elected to stay in Boston but looked emotionally overwhelmed while the top-seeded Celtics dropped the first two games of the series against the eighth-seeded Bulls.

During a two-day break before Game 3, Thomas returned home to Tacoma to be with the family he so dearly yearned to be near in the aftermath of the tragedy. He returned for Game 3 with a bit more vigor, and the mood in Boston's locker room shifted as the Celtics rallied around their leader and took control of the series.

After Friday's victory, Thomas joined a small contingent of Celtics brass, including president of basketball operations Danny Ainge, who accompanied Thomas to Tacoma to attend Chyna's funeral services on Saturday. Before he departed, Thomas implored teammates to focus on preparations for the Washington Wizards and the Eastern Conference semifinal series that opens with a Sunday 1 p.m. ET matinee in Boston.

Thomas said he would do the same after bidding farewell to his sister, who would have celebrated her 23rd birthday next week. Thomas is expected to make the cross-country trek back to Boston on Saturday night with hopes of being ready for Sunday's Game 1, though Celtics coach Brad Stevens has reminded Thomas that he does not have to suit up if he is not emotionally ready after Saturday's services.

"[Saturday's funeral] is a lot more important than [Game 1 on] Sunday," Stevens said. "If it's difficult, it's difficult, but it's just a basketball game. He'll be ready to play. And if he decides when he gets there that it's too much, that's OK. That's fine. This is a lot more important."

After an emotional two weeks following the death of his younger sister, Isaiah Thomas let it all out during the Celtics' series-clinching win Friday night. Jonathan Daniel/Getty Images

The Celtics took great pride in the way they rebounded from that 0-2 deficit to thoroughly dominate the Bulls over the final four games of this series. Friday's win was a laugher in which the Celtics jumped the Bulls early with a 3-point barrage and then tore the game open in the third quarter when Chicago seemed content to slink into the offseason.

Thomas left the Boston bench with a little more than a minute to play to prepare for a late-night dash to Tacoma. Before he left, Thomas took a moment to celebrate in a businesslike Boston locker room, then implored the teammates who wished they could be there with him Saturday to use the off day to prepare for Sunday's Game 1 against the Wizards.

Celtics players expressed their gratitude for the way Thomas performed while averaging 23 points over 34.8 minutes per game in Boston's first-round triumph.

"I know it's been a tough week, but we really thank him for putting that aside and dealing with [basketball] as well," said Gerald Green, one of Thomas' closest friends on the team. "I don't really know how he's able to do it. But we're still with him. And we always will be with him. That’s our leader. I think a lot of guys just said thank you because I think a lot of guys want this as well."

Green says he believes the tenor of the series shifted when Thomas returned from his initial trip home before Game 3. That's also when the Bulls announced point guard Rajon Rondo would be out indefinitely because of a thumb injury, but Thomas had his familiar spunk and really carried the Celtics in the second half of that Game 3 victory in Chicago.

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Thomas didn't shoot the ball particularly well in the series (43 percent from the field, just 20 percent from beyond the 3-point arc), but his imprint was indelible. Thomas had key stretches in all four of Boston's wins.

Teammates know Saturday will continue to bring out the emotions that have been locked inside Thomas for much of the series.

"I know it's going to be hard on Isaiah, but it's our job as his teammates, as his brothers, to make sure we're there for him," Avery Bradley said. "One thing I know about Isaiah is that his mindset is to play for his sister, continue to play the way that he's playing, and to just have fun, and appreciate every day that he's able to wake up. ... I know that's really important. And he looks at life different.

"I look up to him. The way he handled this situation, a lot of people criticized it and say what they want to say, but I respect him a lot. He was able to go through that and still be here for his team and, like I said, play at a high level. So I really appreciate Isaiah. And I'm there for his family. We all are. And we're praying for him. I know that he's going to continue to play hard for his sister."

Bradley recalled how Thomas comforted him when Bradley's mother died unexpectedly before the season started two years ago. Bradley says he believes Saturday's services will be a celebration of Chyna's life and will continue to inspire Thomas to perform in her memory.

"He's gonna have a busy 24 hours," Crowder said. "He's shown he can overcome a lot. We're his family, he's going to be with his family, so I think he'll be able to bounce back. But we know he's going through a lot, and he wants us to prepare, and that's what we're gonna do. We're gonna prepare and, when he gets back, he said he'll be ready to go."