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9/29/2013 1:04 A.M. ET

Gio scratched from Nats' finale for Roark

PHOENIX -- On Sunday, Davey Johnson will manage his last game as skipper of the Nationals. While Gio Gonzalez was going to start against the D-backs, the left-hander was scratched because the Nationals won the first two games of the series, and Johnson is guaranteed to finish his career at least 300 games over .500. He had 1,372 wins to 1,070 losses entering Sunday afternoon.

Tanner Roark will make the start in place of Gonzalez. Roark has seven wins and a 1.74 ERA, and he could be part of the rotation next year.

Even when he was set to pitch, Gonzalez acknowledged he was in shutdown mode and did not want to, deciding to make the start after talking to Johnson. Johnson had said he wanted to go out as a winner and use one of his best pitchers to do it.

"I scratched Go," Johnson said. "It's going to be Roark. Gio is probably real happy about that. He is probably upset that he doesn't get 200 innings. He sure is grinning a lot."

Rizzo in pursuit of manager, key re-signings

WASHINGTON -- Nationals general manager Mike Rizzo addressed the local media Saturday afternoon, and he said the first priority was to hire a manager to replace Davey Johnson. Rizzo declined to give any details regarding the managerial search.

Nationals bench coach Randy Knorr and third-base coach Trent Jewett are considered strong candidates for the job, along with D-Backs third-base coach Matt Williams.

"The manager is going to have an input on what we do with the roster," Rizzo said.

Rizzo mentioned that another priority was to sign shortstop Ian Desmond and right-hander Jordan Zimmermann to extensions. Zimmermann and Desmond were willing to sign extensions last offseason but were not willing to take a team discount.

"Desi is one of our core players; he is one of our leaders on the team," Rizzo said. "If there is a deal out there that we could get done, that would keep him here for the long-term, he is certainly up there in the priority list. But it has to be a deal we could both live with.

"Zimmermann is one of our own. We drafted, developed and signed him. He is one of the good pitchers in the league. We certainly like to keep him long-term."

Rizzo also said he was pleased to see the team play better baseball after the All-Star break. From Aug. 9 up until Friday's game against the D-Backs, the Nationals had a 31-15 record, the best in baseball during that span.

"These guys pulled themselves up on their boot straps, when our low water mark was six games under .500, and we played extremely well," Rizzo said. "To me, that showed the character of a champion, although we didn't play like a champion early enough in the season. But we finished with a flourish, and it's going to set us up well going into the winter and next Spring Training."

Rizzo acknowledged that the Nationals were looking to improve the bench and parts of the bullpen. It is not a secret they are looking for quality lefties out of the bullpen.

Worth noting

• Asked if he would like to manage the Nationals as a player/manager, outfielder Jayson Werth thought about it and said: "That's a tough one. I have to be careful what I say. The answer is yes. But I haven't made a decision if I'm going to put my name in. In the end, I don't think A) I want to manage; or B) I want to be play and manage, just because of the headache of the whole thing. I don't think I want to play and manage at the same time, but I've considered it. I haven't decided to put my name in or not."

Adam LaRoche is done for the season, Johnson said. LaRoche, who has a sore left biceps, hit. 237 with 20 home runs and 62 RBIs.

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashinNats This story was not subject to the approval of Major League Baseball or its clubs.