NBA Star John Wall -- Emotional Tribute to 6-Year-Old ... Who Lost Cancer Battle

Washington Wizards star John Wall fought back tears last night ... after dedicating his performance to his 6-year-old friend Miyah Telemaque-Nelson who died of cancer Monday morning.

"This is an emotional game for me," Wall said following the win against the Celtics ... "This is for Miyah ...one of my close friends that I lost that I met last year."

Wall and Miyah were pretty tight -- and he helped her meet Nicki Minaj back in March.

"I can't believe this little angel is gone," Minaj wrote Tuesday morning ... "When I met her she was recovering."

"Sending love to her mother and family and John. This is heartbreaking. She was so full of life. #RIPMiyah."