Referee Greg Willard has cancer

Greg Willard has been officiating NBA games for two decades. AP Photo/Michael Conroy

NBA referee Greg Willard, who was scheduled to work Wednesday's Spurs-Thunder game before being replaced due to illness, has been diagnosed with pancreatic cancer.

Referees during the Finals will wear No. 57, Willard's number, on their jerseys to recognize the veteran official, the National Basketball Referee Association said.

Willard worked games in this season's playoffs, including one just last week between the Miami Heat and Boston Celtics.

Willard has been an NBA referee for 24 years and has worked the Finals since the 2009-10 season.

"Greg's professionalism and integrity have made him a role model within the NBA community," said NBRA general counsel Lee Seham. "We want him and his family to know that our thoughts and prayers are with them."

A source told ESPN The Magazine's Ric Bucher after Willard was pulled from Wednesday's game that a blood test revealed the possibility of a serious illness.