The American, who played fringe roles for a myriad of NBA teams before joining Serbian champions Partizan Belgrade last July, shrugged off an ankle injury to help Olympiakos to a 62-61 win over CSKA Moscow in Sunday's rip-roaring Euroleague final.
Trailing by 19 points midway through the third quarter, Olympiakos looked doomed before Law took centre stage and inspired the stunning comeback with steely defence on CSKA's Serbian point guard Milos Teodosic.
"Law is the unsung hero of our success because after the semi-final win over Barcelona on Friday, his ankle was in such a bad shape he couldn't walk down the stairs from his hotel room for meals," Olympiakos coach Dusan Ivkovic said.
"He played through the pain and was instrumental in the fightback because CSKA's offence was ground to a halt when he came off the bench," said the 68-year old Serb who also coaches his country's national team.
Law struggled at Partizan, who axed him after they failed to reach the second group stage of the competition, and it seemed he would spend the second half of the season on the sidelines.
He was hired by Olympiakos in January during the winter break and his speed as well as the ability to shoot with both hands helped the team break into the Euroleague quarter-final playoffs and then the Final Four as underdogs.
His contribution in the upsets of Barca and CSKA Moscow, where he got the better of big-money signing Teodosic at crunch time, was a fitting finale in a rollercoaster season for Law.
"I am a European champion, I feel like I am on the top of the world now and no one can take that away from me," the 27-year-old told Reuters with a broad smile on his face after lifting the trophy.
"It's something everyone has to respect and it will stay in my biography forever.
"After the Partizan experience, I didn't know how I would fit in at Olympiakos but the coach made it easy for me because he is an expert in bringing the best out of players.
"I knew Olympiakos was a talented team and the staff did a great job putting the pieces together."
Moments after the biggest accomplishment of his career, Law was uncertain about his future.
"I haven't had the time to think whether I will stay at Olympiakos. I will let my agent handle it because now is the time to celebrate."