Stephen Strasburg is making progress.. (Photo by John McDonnell / The Washington Post)

A little after 1 p.m. Friday afternoon, Stephen Strasburg was throwing off a mound in the bullpen beyond the right-field wall at Nationals Park. He was not warming up to start Game 1 of the National League Division Series, which was slated to begin about four hours later. A couple months ago, Strasburg was in contention to make that start for the Washington Nationals. Then he suffered another elbow injury, fleetingly wondered if his career was in jeopardy, and was ruled out for at least the NLDS for the second time in five years.

Yet Strasburg, usually stoic, was in high spirits while his teammates prepared to open the postseason against the Dodgers because he successfully completed his first bullpen session since exiting a game exactly one month earlier with a pinch in the back of his right elbow. The development is a significant step in his quest to rejoin the Nationals should they advance in the playoffs.

“I keep telling myself that,” Strasburg said. “That’s why I’m not just shutting it down. I’m working hard every single day to hopefully be in a position to pitch. But I can’t speculate on that at this point.”

Strasburg threw 25 pitches, all fastballs and changeups, with pitching coach Mike Maddux closely examining from a few feet away. He didn’t go full throttle, but he worked up a sweat. He said he is scheduled to throw another bullpen session Monday.

“They wanted me to go in there at 50 percent, but 50 percent is basically trying to throw 45 miles an hour so I didn’t really understand that,” Strasburg said. “I would say it was crisp and I was letting it go.”

Strasburg, 28, admitted he briefly thought he was bound for a second Tommy John surgery as he walked off the field with one out in the third inning against the Atlanta Braves on Sept. 7, which would’ve put his career in peril five months after signing a seven-year, $175 million contract extension.

“I try to change this about me, but I automatically assume the worst,” Strasburg said.

He avoided that and the club termed the injury a strained flexor mass. But Strasburg specified Friday that he was diagnosed with a partial tear of his pronator tendon, which is connected to the flexor mass. He said he developed weakness in the flexor mass over an extended period of time, probably a couple months, and it might have led to the pronator tear. Strasburg said he sought a second opinion from Dr. Neal ElAttrache and the tear didn’t require surgery. The remedy was time to heal and it did with the help of a platelet-rich plasma injection.

“At this point now, when I play catch, I’m not really thinking about it,” said Strasburg, who started the season 13-0 and finished 15-4 with a 3.60 ERA. “I’m letting it go. It feels good. Now the question is: How fast can I get it built back up? And how fast can I get it built back up safely?”

The Nationals want him to build up fast enough to pitch in the next round, should they advance past the Dodgers. Game 1 is scheduled for Oct. 15. Washington would have to deem him available by then, which could be for a limited workload, to put him on the roster for the series or risk wasting a valuable spot.

Washington probably would want Strasburg to face hitters before then, following a protocol similar to what Joe Ross recently completed in his return from a shoulder injury. Strasburg said sending him to instructional league in Florida “might’ve been the plan,” but the league was cancelled because of Hurricane Matthew so he doesn’t know when and where he’ll face batters.

For now, he’ll stick to his throwing program and take the mound again Monday. And if the Nationals can get past the Dodgers without him, he hopes to have another chance to pitch in the postseason four years after he his notorious shutdown.

“The first time was weird because I didn’t know any better and I wasn’t hurt,” Strasburg said. “From a personal standpoint, it is tough to not be out there to compete with the guys. But I got to put the personal side away and be a good cheerleader, at least for now, and I have a lot of confidence that they’re going to get the job done. Hopefully, I’ll be ready to go when it’s my turn.”