Manningham began practicing this week for the first time since last December, and could be further along in his comeback than originally anticipated.
"I don't have a crystal ball on exactly when he plays in a game," Jim Harbaugh said Friday before the team took off for Tennessee.
"He looks really good, really good. He had a really good day yesterday. Excited for him."
Manningham told reporters earlier in the week his inability to practice has taken its toll on him mentally, but it appears to have him driven to come back even more explosive than before.
"I'm just trying to get confidence back, stay right upstairs," Manningham said. "You can get caught up in not playing. Just trying to keep my attitude positive."
The former Michigan Wolverine and New York Giant was San Francisco's second leading receiver last season, catching 42 balls for 449 yards and a touchdown before sustaining his injury in Week 15's 42-13 drubbing in Seattle.
His absence has been felt in the passing game, as Colin Kaepernick hasn't had the luxury of a true No. 2 wideout opposite Anquan Boldin. Kaepernick has a 32.68 QB rating while targeting Kyle Williams, Jon Baldwin, Marlon Moore and Quinton Patton with no touchdowns and a pair of interceptions. Alex Smith and Kaepernick combined to have a 98.2 rating when targeting Manningham in 2012.
The 49ers have an open roster spot that they plan to fill Saturday after releasing receiver Chris Harper. But it's unlikely they would use the opening on Manningham considering their injury status along the defensive line.
The logical option would be Mike Purcell, a nose tackle off the practice squad who would get time if Glenn Dorsey is unable to go after straining his hamstring against the Cardinals. Dorsey practiced Friday but is officially listed as questionable for Sunday.
The less-likely option is rookie Quinton Dial, who partook in his first ever pro practices this week. The fifth-round pick spent the offseason recovering from toe surgery following his season at Alabama.
The Titans boast the league's No. 10 defense in terms of yards and have excelled in getting the field, holding offenses to a third-down conversion rate of just 29.87 percent. That's been an area where the 4-2 49ers could use Manningham's ability to get open in small spaces. San Francisco is ranked 23rd converting just over 35 percent of third downs.
It would seem logical to let Manningham practice for the full three weeks before he has to be reinstated on the 53-man roster Nov. 5, otherwise he would have to be shut down for the season. Following this weekend's game in Nashville, the 49ers take off for London to play the win-less Jaguars before their bye week. They host Carolina Week 10.
But if Manningham is looking as good as Harbaugh claims, he could make his season debut against Jacksonville across the pond.
"It's going to be soon," Harbaugh said.
*Statistics from Pro Football Focus were used in this report*
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