PITTSBURGH -- Pirates right fielder Gregory Polanco 's breakout season is over.

Polanco sustained a "significant" bone bruise in his left knee that will require six to eight weeks of rest and rehabilitation, the Pirates announced on Saturday. He also injured his left shoulder while awkwardly sliding into second base on Friday night, though the details of that injury remain unclear.

The Pirates are seeking a second opinion to determine the best course of treatment for Polanco's undisclosed shoulder injury, according to a statement from the team. He injured himself while sliding into second in Pittsburgh's 5-3 win over the Marlins on Friday at PNC Park. He jumped to start his slide, and his left leg bent uncomfortably as his right foot hit the ground first. He held onto second base with his left hand as he rolled past the bag.

It is a disappointing end to Polanco's mostly encouraging season. He started 50 of the Pirates' last 52 games before Saturday and took great pride in his health this year after playing only 108 games last season.

"This is another learning opportunity. You don't like it, but you're going to have to deal with it," manager Clint Hurdle said. "The reality of it is we're going to have to deal with it. He's going to have to deal with it. The challenge now will be to go through the rehab, to go through the build back, to come back bigger, better and stronger than ever before."

Polanco battled through his fair share of slumps at the plate, but he still put together his best overall offensive campaign in the Majors and established himself as the Bucs' most productive hitter. Polanco hit .254/.340/.499 with a team-leading 23 home runs and 81 RBIs in 130 games.

"He had made great strides," Hurdle said. "I really thought the improvement and the maturity -- and that's the word I'll continue to use -- he showed throughout the season, being an anchor in the lineup, continuing to work on his defense, stealing bases even in the month of September. He was intentional with all his work across the board."

Polanco had established himself as Pittsburgh's No. 3 hitter. Starling Marte , who has hit leadoff lately, will likely move down toward the middle of the order with Adam Frazier taking over atop the lineup.

The Pirates likely will rotate a cast of outfielders into his spot over the final three weeks of the season. Jordan Luplow , who started in left field on Saturday, should receive most of the playing time. Frazier and fellow super-utility man Pablo Reyes , who started in right against the Marlins, could also factor into the mix.