SAN FRANCISCO -- Jayson Werth was back in the Nationals' lineup Tuesday night. Perhaps more surprisingly, Michael Morse was not.

Werth reported to AT&T Park in good spirits, walking without a boot on his sore right ankle and saying he felt "much better" than he did Monday, when he was a late scratch from Washington's lineup. Werth underwent a precautionary MRI on the ankle Tuesday morning, and the results came back negative.

Nationals manager Davey Johnson wasn't 100 percent confident when he met with reporters that Werth would be at full strength, but he was not scratched from the lineup after going through batting practice before the game.

Morse, on the other hand, was held out due to a jammed right thumb and may not return until Friday. Morse exited Monday night's 14-2 win early after jamming the thumb during batting practice, though he said after the game he expected to play Tuesday.

"The big guy is down. His big thumb is barking," Johnson said. "Probably the cooler weather doesn't help that. I guess it got jammed too many times."

Johnson hoped to start Morse against Giants right-hander Tim Lincecum in Wednesday's series finale but acknowledged he may not return until Friday's series opener against the Mets, giving him an extra day to rest.

"If he's able to go [Wednesday], I'll definitely have him in there," Johnson said.

Nationals eyeing Friday return for Desmond

SAN FRANCISCO -- The Nationals have a potential return date set for shortstop Ian Desmond, and it's a bit sooner than expected.

Washington's All-Star shortstop will be activated for Friday's series opener against the Mets, provided he gets through his full pregame workouts Tuesday and Wednesday and a simulated game Thursday without incident.

Desmond went through his first regular pregame workout Monday and took early batting practice Tuesday. He was scheduled to go through two more full workouts at AT&T Park before participating in a sim game against injured pitcher Chien-Ming Wang.

If Desmond comes through that in good health, Nationals manager Davey Johnson won't waste time getting him back in the lineup, although it will present Washington with a difficult roster decision.

"I plan on, unless Mike Rizzo ties my hand behind my back, activating him. So I'll keep my fingers crossed," Johnson said. "He's a horse. I want him back. We all want him back."

Desmond was in good spirits after his early hitting session, to the point that he pulled a good-natured joke on his manager. Desmond went into Johnson's office and said, "I'm hurting." Fearing another injury or a setback, Johnson replied, "Oh, no. How bad is it?"

"He said, 'My ears are hurting from the loud sound coming off my bat,'" Johnson said. "He got me. ... That was a good sign."

Rendon moves up, could earn September callup

SAN FRANCISCO -- Anthony Rendon, the Nationals' top pick in the 2011 First-Year Player Draft, was promoted to Double-A Harrisburg on Tuesday. And, at least as far as manager Davey Johnson is concerned, it's not off the table that he'll be in the Majors come September.

Rendon, the No. 6 overall pick in 2011 out of Rice University, was promoted to Harrisburg from Class A Potomac. The 22-year-old got a late start to the season due to a badly sprained left ankle but posted a .333/.438/.630 batting line in nine games with Potomac.

"I think it's great," Johnson said of Rendon's promotion. "As long as he's healthy, that stroke of his will hunt at most levels. That's good."

Could Rendon climb all the way to the Major League roster by September? It would appear unlikely, given his late start and his lack of experience in the Minors.

But he already has a spot on the Nationals' 40-man roster, and Johnson wouldn't eliminate the possibility that Rendon could make his way to Washington once the active rosters expand from 25 to 40 players.

"He might be. We'll see how he finishes up," Johnson said. "This is the year of the young guys all around baseball, and he's another one right in that mold. ... He might be old for the young guys."

Worth noting

• Wang will be evaluated after Thursday's sim game with Desmond, and the right-hander will "more than likely" restart his Minor League rehab assignment after that. Wang exited his last rehab assignment Wednesday, complaining of right hip soreness after a particularly rough outing Tuesday night.

• By picking up his 15th victory in Monday night's 14-2 rout of the Giants, Gio Gonzalez tied Livan Hernandez for the most single-season wins in Nationals history. Hernandez went 15-10 in 2005.

• Johnson drew some laughs from the small crowd of reporters in the visiting clubhouse at AT&T Park on Tuesday afternoon when asked whether Morse was scheduled for an MRI or X-ray for his jammed thumb.

"I'd hate to be paying our MRI bill," Johnson joked, making light of his club's slew of injuries this year. "It seems like every time we turn around, somebody's getting one."