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6/21/2014 10:31 P.M. ET

Clippard feeling confident, no matter opponent

WASHINGTON -- Heading into Friday night's matchup with the Braves, Nationals reliever Tyler Clippard had surrendered at least one run in eight of his previous nine appearances against Atlanta over the past two seasons.

But when the right-hander entered in the top of the 11th inning Friday night, he retired the Braves in order, including strikeouts of Jason Heyward, who had hit a two-run double earlier in the game, and Chris Johnson, who tallied three RBIs in Atlanta's 3-0 win on Thursday.

"I've been feeling good on the mound," said Clippard, who went 25 straight appearances without giving up an earned run before June 17. "It doesn't really matter what team it is. I feel comfortable throwing the fastball for strikes, pretty much where I want to, for the most part. That just gives you confidence against anybody, when you're able to do that."

Harper could start rehab stint as early as Monday

WASHINGTON -- A Major League source said Saturday night that Nationals left fielder Bryce Harper (torn thumb ligament) will begin a rehab assignment with Class A Potomac on Monday. But manager Matt Williams didn't confirm the claim before the game vs. Atlanta.

"I heard a vicious rumor going around that he's going out Monday," Williams said. "Is that his plan? Because nobody told me."

Williams did say Harper would leave for an assignment at some point during the Nationals' upcoming road trip, which starts on Monday. Williams didn't rule out Monday as a potential start date for Harper's rehab stint, but he said it could also be Friday, for that matter. Harper was not available for comment.

When he begins his assignment, Harper will go through a standard progression over the course of around seven games, starting with five innings before moving to seven and then nine. If Harper did start Monday, he would play games that day and Tuesday before an off-day on Wednesday to evaluate his thumb. Williams said Harper would get at least one nine-inning game as a designated hitter before playing a nine-inning game in the field.

Williams said Harper would play all three outfield positions at some point during the rehab assignment, something Harper will likely do when he returns to the Major Leagues. If all goes according to plan, Williams said Harper would return during the Nationals' next homestand, which begins June 30 against the Rockies.

Williams said the key is for Harper, who has been sidelined since April 25, to return to game shape. That process will produce some residual soreness, which Williams said is expected for a rehab assignment of this significance.

"We'll bubble-wrap him as much as we can," Williams said. "But we've got to let him go, too. We've got to let him go out there and compete."

Williams: Nats not calling Strasburg's pitches

WASHINGTON -- The Nationals' game plan for Braves outfielder Jason Heyward was made apparent Friday night when right-hander Stephen Strasburg threw 18 fastballs out of 19 pitches to Heyward in three at-bats.

Strasburg struck out Heyward in the first at-bat on six fastballs in the top of the second inning. Heyward responded with a single off a fastball in the top of the fourth inning before ripping a two-run double over the head of Jayson Werth in right field on yet another fastball in the fifth inning to give the Braves a 4-1 lead in an eventual 6-4, 13-inning victory.

After the game, Strasburg commented on the approach.

"I guess it was the plan going in," Strasburg said. "I don't think it's the right plan. But that's what we went with."

On Saturday, manager Matt Williams responded to Strasburg's claims.

"He who holds the ball controls the game," Williams said. "We have advanced reports with reams of information. Those reports are condensed, and information is given to everybody about how we can get a guy out. But it's about feel for Stephen. If he feels like he can throw a fastball somewhere to get a guy out, then he's going to do that. If he doesn't feel like that's what he's going to throw to get the guy out, then he'll go to something else. So I would chalk [the comment] up to heat of the moment."

"We're certainly not calling pitches for him," Williams continued. "We're not telling him, 'You have to throw this or that.' It's about what he feels out there."

Worth noting

• Wilson Ramos (strained hamstring) went 1-for-3 with a three-run home run in his first rehab start for Double-A Harrisburg on Saturday night. Ramos started the game at catcher and played five innings. He grounded out to third and struck out looking in his other two at-bats. 

• Williams made batting practice optional for the Nationals on Saturday to provide his players with a chance to rest. Both games against the Astros on Tuesday and Wednesday lasted nearly four hours, while Friday night's game against the Braves went 13 innings.

"There's been a lot of grinding going on the last four days," Williams said. "You just try to give them the opportunity to step back for a minute and not force anything on the field."

Daniel Popper is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.