The Pirates announced Sunday that manager Clint Hurdle has been relieved of his duties and will not return after nine seasons with the club.
Ken Rosenthal of The Athletic was the first to report that Hurdle was on his way out. General manager Neal Huntington would remain in his role.
Pittsburgh is 69-92 coming into the final game of the season against the Reds and is in danger falling short of 70 wins for the first time since 2010, the last season before Hurdle took over.
The club went 57-105 in that season before Hurdle's arrival and turned into a playoff team by his third season. The club made three straight postseason appearances under Hurdle, but failed to get past the NLDS and lost in the NL wild-card game twice.
"Words cannot express how much respect and appreciation I have for Clint as a person and a leader. He was the right person at the right time to take on the enormous challenge of leading our Major League team out of an extended losing streak and piloting us to three straight postseason appearances. We will be forever grateful for his dedication to the Pirates organization on and off the field," Huntington said in a statement. "This was an extremely difficult decision for us. As an organization, we believe it was time for a managerial change to introduce a new voice and new leadership inside the clubhouse.
"This has been a challenging season on many levels. We are committed to assessing and improving upon our operations at all levels in order to return Postseason baseball to Pittsburgh."