John McDonnell/TWP

The Nationals placed third baseman Ryan Zimmerman on the disabled list with a strained left hamstring and called up top prospect Anthony Rendon to take his roster spot, a temporary swap of their franchise pillar for the 22-year-old who may one day replace him.

The Nationals expect Zimmerman to miss the minimum 15 days on the disabled list, a stay that can be backdated to Thursday. While Zimmerman sits, Manager Davey Johnson plans to start Rendon at third base. Rendon will be in the Nationals’ lineup Sunday afternoon, likely hitting sixth against New York Mets right-hander Dillon Gee.

“I’ll be his biggest fan,” Zimmerman said. “We need him to come up and do as well as he can to help us win. That’s the ultimate goal. It’s a team. This is one of the first speed bumps we’ve had, and hopefully Anthony can come up – I know he can come up – and do fine.”

Following a splendid showing during spring training, Rendon has hit .292/.462/.500 in 14 games at Class AA Harrisburg. Rendon missed the majority of his first professional season with a fractured ankle, but when healthy his smooth fielding and picturesque swing have validated the Nationals’ decision to take him with the sixth overall pick in 2011.

“I don’t like to bring a youngster up and have him sit,” Johnson said. “He’s been swinging the bat pretty good down there. It’s no slight against some guys I got here.”

After the Nationals’ 7-6 victory Saturday afternoon, 20-year-old Bryce Harper smiled when told Rendon would be joining the Nationals.

“I’m excited,” Harper said. “That’s awesome. It sucks that Zim is going on the DL, but I’m excited for Rendon to get up here. I think he’s a special talent, and it’s exciting to have a guy like that. It’s going to be fun to watch him play.”

Johnson and General Manager Mike Rizzo both said they expect Rendon to return to the minors when Zimmerman comes off the disabled list. But Rizzo also said he would keep an open mind and let the situation play out.

“I would think that when Zim comes back, we’ll probably send him down for more seasoning,” Rizzo said. “But we’ll take that as it comes. We see him as a long-term component of the team.”

Zimmerman’s trip to the disabled list comes after a difficult week for the third baseman. His throwing ability came under scrutiny after he made four throwing errors in five games. The issue raised speculation about an eventual switch to first base in order to make room for Rendon. The changing of the guard happened, but only temporarily, the Nationals insist, and not because of performance.

“It has nothing to do with” Zimmerman’s throwing, Johnson said. “I don’t mess around with hamstrings. All he needs to do is take one step and pull that puppy, and then it’s a couple-month deal.”

Zimmerman received an MRI Saturday. Doctors recommended he rest for 10 days. Zimmerman has already sat for three, but the Nationals did not want to be left short-handed as Zimmerman healed.

“The results weren’t necessarily a bad thing,” Zimmerman said. “Nothing wrong would have been the best-case scenario, but we knew something was wrong. I can’t put the team or put Davey at the disadvantage of being on the bench for seven to 10 days. You can’t do that. Take the time to get it right because it’s only April, and I’ll be good to go.”

Zimmerman landed on the disabled list for the third straight season, and for the second straight year the Nationals replaced him with the splashiest option at their disposal. Last season, the Nationals called up Harper to take his place.

“Now,” reliever Criag Stammen said, “we have two all-star kids.”