Retired NBA All-Star point guard Gilbert Arenas was a tenacious player on the hardwood, and sometimes the fiercest competitor he faced off against was not even an opponent but an official.

Arenas, 38, answering queries online in a Reddit Q&A, called out former NBA referee Joey Crawford as the “hardest” person to score on in a game.

“[The] referees [were the hardest to score on],” Gilbert Arenas wrote on Reddit, via Bleacher Report's Tyler Conway. “Joey Crawford was the hardest to score on. [T]hat muthaf* had some great defense.”

Arenas, originally a second-round selection of the Golden State Warriors who won Most Improved Player in 2003, spent his peak years with the Washington Wizards, earning three consecutive All-Star selections in 2005-07. Arenas took the Wizards to the second round of the playoffs in 2005, the furthest the franchise went in the postseason since the 1981-82 season.

Arenas later played briefly for the Orlando Magic before being waived in Dec. 2011 and wrapping up his NBA tenure with a 17-game stint with the Memphis Grizzlies in 2011-12. “Agent Zero” spent a single season, 14 games, with the Shanghai Sharks in the Chinese Basketball Association.

Crawford, who officiated in the NBA for nearly 40 seasons, was one of the more well-known referees due to his combative nature with players and coaches along with a proclivity to dish out technical fouls. Crawford retired from refereeing in 2016.

Arenas clearly had an issue “working” with Crawford, who was patrolling the sidelines during the All-Star point guard's NBA career, seeking to penalize players committing infractions.