PITTSBURGH -- Cubs shortstop Starlin Castro singled in the fifth inning on Friday for his 500th career hit, becoming the 28th player in Major League history to reach that milestone before the age of 23.

Castro, 22, singled in the third for hit No. 499, and then singled with two outs in the fifth for No. 500.

The only other active player on the list is the Yankees' Alex Rodriguez.

Others to reach the milestone at such a young age include Ted Williams, Hank Aaron, Al Kaline, Mickey Mantle, Robin Yount, Ty Cobb, Johnny Bench, Orlando Cepeda and Ken Griffey Jr.

Since Castro made his Major League debut on May 7, 2010, he leads all National League players in hits. The Brewers' Ryan Braun was next with 490 hits entering play on Friday.

Jackson sustains bruised knee on great catch

PITTSBURGH -- Cubs rookie Brett Jackson is day to day with a bruised right knee sustained during a collision with the center-field wall at PNC Park on Friday.

Jackson had some minor cuts to his face after hitting the wire mesh fence near the visitors' bullpen as he grabbed Andrew McCutchen's fly ball to end the sixth inning and strand two baserunners.

The rookie had failed to snare Pedro Alvarez's fly ball at the wall in center in the fifth, resulting in a double and the only hit in six innings off Cubs starter Travis Wood.

"I was [ticked] I missed the first one," Jackson said. "It's almost inexcusable. I've got to catch that ball, and I wasn't going to let another one drop. I was joking with Travis and told him he wasn't going to go nine innings. He said he would've. I was disappointed I didn't catch that first one."

After making the catch, Jackson lay on the ground for a few minutes, and admitted he was "seeing stars." His teammates, Cubs manager Dale Sveum and the athletic trainers ran to him.

"I was very scared, because he hit the fence very hard," Alfonso Soriano said. "Thank God he's OK. I hope in a couple days, he's back."

Jackson was able to walk off under his own power, with a trainer on each side. He was due to lead off the Cubs' seventh but was lifted from the game for pinch-hitter Tony Campana.

The medical staff told Jackson it was a good thing he was in the air when he hit the wall. If his foot had been on the ground, he might have blown his posterior cruciate ligament.

"Whatever my knee hit didn't give," Jackson said of the metal post.

His right knee was bruised and bleeding from the collision. Apparently, Jackson isn't afraid of making contact with inanimate objects.

"I've been fairly lucky with injuries throughout my career," Jackson said. "I've hit walls pretty hard and tweaked stuff here and there, but nothing too serious ever -- knock on wood. It's important to play the outfield without fear, it's important to play the game without fear. That doesn't mean I'm 100 percent fearless."

Samardzija to be shut down following Saturday start

PITTSBURGH -- Jeff Samardzija has been trying to convince the Cubs all season that he can handle the workload of a big league starter. However, the team decided Samardzija has thrown enough innings, as the right-hander will make his final start on Saturday.

When Samardzija takes the mound against the Pirates, it will be his team-leading 28th start. He already has 165 2/3 innings, which is nearly as many as he had in the big leagues coming into the year (169 2/3) and double what he threw last season as a reliever (88). There's nothing wrong and Samardzija is healthy, but the team is looking to next year.

"It's unfortunate," Samardzija said Friday. "I really would've liked to finish the season, and that way I could look back and see how I went from beginning to end. You have to respect what they're planning on doing and what their plans are for the organization and the team. I talked to Dale [Sveum, manager] about it, and I put a lot of my faith in him, and in [pitching coach Chris] Bosio, too, that this is the right move for the right reasons."

Samardzija, 27, got a head start on the other Cubs pitchers by throwing before Spring Training began. Those innings, plus the 24 he had in Cactus League play, will put him at 200 in his first season as a starter.

"We all witnessed the gradual climb he made and the adjustments he had to make, and he did it all," Sveum said. "He got stronger than we expected. He, obviously, didn't go backwards. He had the second-half numbers to prove that, and going into the seventh inning pretty much every time out.

"He did everything we imagined, and even more," Sveum said.

Samardzija has 16 quality starts, and after going 6-8 with a 4.71 ERA before the All-Star break, he is 2-5 with a 2.66 ERA since.

The right-hander is very competitive -- after all, he was an All-American wide receiver at Notre Dame -- but Sveum said he took the news fairly well.

"When you put it to him with all the extra work he put in to becoming a starter, and all the throws he made before Spring Training to prepare, it even made sense to him in a way," Sveum said. "You can't blame him -- we want that guy to be our [No. 1 or 2] guy when everything is fixed here. We want him to be healthy, strong and able to pitch in October."

"It's going to be tough watching," Samardzija said. "It's not something I'm accustomed to. I'm used to playing, and I'm used to playing all the time."

Not only could Samardzija be one of the Cubs' top starters, he could be on the mound for Opening Day 2013.

"Obviously, we have to see what we have going into next season," Sveum said. "Right now, for what we have on our roster now, you'd have to figure him to be a candidate for the No. 1 spot, no question about it."

"That would mean a lot," Samardzija said. "It's already meant a lot this year from where I've come in Spring Training."

It's tough to be shut down when he's feeling healthy and strong.

"That makes it hard, but it also makes it hard leaving your team," Samardzija said. "I'm not leaving the team, but when you're in a tough spot, you need everybody to step up and do their part. I want to be out there pitching every fifth day, and you want to end the season with a full season."

Samardzija will spend the final weeks evaluating what he did and determining the best offseason program, as well as helping the young pitchers go over their game plans. Samardzija most likely won't be throwing as many innings before Spring Training, but he does plan on getting a head start. And next year, there will be no restrictions.

"I'll believe that right now, and that's why we're doing this year," Samardzija said. "If we want to win games, hopefully, they want me to do that, and pitch every fifth day with no extra rest."

No penalties yet stemming from fracas with Nats

PITTSBURGH -- Major League Baseball has yet to issue any penalties to Cubs bench coach Jamie Quirk, catcher Steve Clevenger or pitcher Manuel Corpas, who were all ejected from Thursday's game against the Nationals in a wild fifth inning.

Quirk was ejected first after a shouting match with Nationals third-base coach Bo Porter that appeared to be prompted by Jayson Werth swinging at a 3-0 pitch when his team had a five-run lead. Clevenger and Corpas were tossed following a bench-clearing fracas on the field after Cubs pitcher Lendy Castillo threw inside to Bryce Harper.

Some teams seem to be sparked by a little dustup.

"I've seen it happen before," Cubs manager Dale Sveum said. "It usually actually works for the better. You don't want things like that to happen, but it's part of the game. Usually in 162 games, something like that will happen. A lot of times in my career, that has rallied a team together and the team starts playing better."

Sveum remembers at least two brawls doing just that -- one while he was with the Brewers and another when he was with the Red Sox.

Did Sveum feel Werth violated one of baseball's unwritten rules in his at-bat?

"I didn't think so, no," Sveum said. "It was the fifth inning. I don't expect my team to stop playing in the fifth inning. I didn't have any problem with anything they did."

Cubs claim right-hander Berken off waivers

PITTSBURGH -- So, with Jeff Samardzija being shutdown after Saturday's start, who takes his spot in the Cubs rotation?

On Friday, the Cubs claimed right-hander Jason Berken off waivers from the Orioles, and he will be slotted into the rotation.

Berken, 28, was 5-6 with a 3.50 ERA in 26 starts for Triple-A Norfolk, walking 39 and striking out 98 over 144 innings. He had a 1.35 ERA in four April starts, and finished well, compiling a 3.00 ERA (12 earned runs over 36 innings) in six August starts.

Berken made a relief appearance for the Orioles in May before being optioned back to the Minor Leagues. He was the Orioles' sixth-round pick in 2006.

To make room on the roster, the Cubs placed right-hander Blake Parker on the 60-day disabled list with a bone contusion in his right elbow. Parker had been sidelined earlier this season with a stress reaction in his elbow.

Class A Boise trying to stay alive in playoffs

PITTSBURGH -- Class A Boise will try to even its best-of-three Northwest League Championship Series on Saturday when it plays host to Vancouver. Balbino Fuenmayor hit a go-ahead two-run single in a seven-run seventh inning to lift Vancouver to a 10-7 victory over Boise in Game 1 on Thursday.

Marco Hernandez had three hits, Daniel Vogelbach drove in three runs, and Jeimer Candelario hit a single and a double for Boise. Hayden Simpson took the loss, giving up three runs on two walks. He was unable to retire a batter.

Right-hander Pierce Johnson, selected in the compensation round of the June First-Year Player Draft and ranked No. 9 on the Cubs' Top 20 Prospects list, was slated to start Game 2 on Saturday.