Jones revealed this week that he hasn't played since the Aug. 22 preseason game because of a racing heartbeat that would not settle down. He was cleared to return to practice this week and has been limited in workouts. Marcus Spears replaced Jones in the starting lineup in the season opener.
"He didn't get too out of shape," Harbaugh said. "He's progressing well. We're going to have to see how he feels on Sunday. He looked OK at practice. But that's something we're going to have to see how he's feeling on Sunday. So, he's got a chance."
Harbaugh also addressed the team's decision to place rookie wide receiver Aaron Mellette on injured reserve Wednesday. There were questions about Mellette's knee injury, because he wasn't on the injury report last week and he didn't play in the season opener.
According to Harbaugh, Mellette's knee bothered him throughout training camp, and the seventh-round pick had to sit out when the knee swelled up. Harbaugh said Mellette learned he had two cartilage tears after seeing a specialist.
"It's not major, major," Harbaugh said. "But they're four-to-six week deals, and we don't really have time for that in terms of holding a roster spot. So, we figured we'd go and make the roster move and get him healthy."