Manager Dusty Baker said today that Ross still needs to make another minor league rehab start before coming off the disabled list to face big league hitters. The time and place of that start is still being sorted out.
"We're not sure yet," Baker said. "He'll probably go out and throw again. We'll see how he comes out of that. We need to get him some length and some quality at the same time."
Out since July 3 with right shoulder inflammation, Ross has made two rehab starts so far. He tossed three scoreless innings for Single-A Hagerstown on July 24, then went 4 2/3 innings for Triple-A Syracuse on Saturday, allowing three runs and seven hits.
The primary issue at this point is stamina; Ross only threw 67 pitches in his most recent start, and the Nationals would like him to build up to at least 80 or 90 before activating him off the DL.
Who that leaves to start Friday night at Nationals Park remains unclear. Because of off-days, the club could just keep their four healthy starters on regular rest and not use a fifth starter for another two weeks if they want.
But for now, the Nationals are listing Friday's starter as "TBD" against the Giants' Jeff Samardzija, with Gio Gonzalez facing Matt Cain on Saturday and Stephen Strasburg battling Madison Bumgarner in a star-studded Sunday series finale.
Barring a last-minute change, the Nationals would either need to promote prospect Lucas Giolito from Syracuse - fellow right-hander Reynaldo Lopez can't be recalled yet, unless he's replacing an injured player - or use long reliever Yusmeiro Petit as a fill-in starter.
Any call-up would require a corresponding roster move, with the club needing to drop either a reliever or a bench player.
Update: Three innings are in the books, and the Nationals hold a 1-0 lead. That's because Trea Turner launched a 451-foot homer to left-center in the top of the third. The kid's first homer of the year was a monster shot, second-longest on the team this season. He packs quite a punch in that slender frame of his. Max Scherzer, meanwhile, has cruised through his first three innings, issuing only a leadoff walk to Michael Bourn in the bottom of the first ... and nothing else since.
Update II: We're through the sixth inning now, and the Nats have opened up a 4-2 lead. The Diamondbacks briefly tied the game in the fifth on a strange play. With the infield drawn in with a runner on third, Bryce Harper had to come charging way in from right field on a popup barely beyond the infield dirt. He couldn't get there in time, so the tying run scored. No problem, though, because Daniel Murphy crushed a solo homer in the top of the sixth to regain the lead. That's Murphy's 21st homer and 80th RBI. And then, just for good measure, Scherzer delivered a two-out, two-run single up the middle on an 0-2 pitch, extending the lead to 4-1. Jake Lamb did get a run back in the bottom of the inning with a solo homer into the pool at Chase Field, but Scherzer otherwise continues to look sharp. It's 4-2 heading to the seventh.
Update III: Well, now it's 4-3 after seven innings, thanks to Yasmany Tomas' towering homer off Scherzer. It came on a first-pitch curveball, and Tomas wasn't fooled by that in the least. Scherzer has given up two solo shots today. He also has struck out 10 and walked only one. He's at 92 pitches entering the eighth. What does Dusty Baker do?
Update IV: It's over. Nats win 8-3 after adding four insurance runs in the top of the ninth. Scherzer went eight innings to improve to 12-6. Mark Melancon was ready to pitch in a save situation, but wound up just getting some work in with a five-run lead. The Nats swept the series, finished 6-3 on the road trip and head home with a seven-game lead in the NL East.