Collins was limited as the Titans worked Wednesday indoors in a practice that mostly was a walkthrough.
"He's much better -- actually he's better than he was Sunday, which is encouraging," Fisher said.
Rookie Rusty Smith started last Sunday and struggled, throwing for just 138 yards with three interceptions in a 20-0 loss to the Houston Texans. Regular starter Vince Young is out for the season after he tore the flexor tendon in the thumb of his throwing hand during a Nov. 21 overtime loss to the Washington Redskins.
According to Fisher, Collins' potential return has been "a significant boost" to Tennessee's offense, which can do more with the veteran than Smith.
"Guys are excited," the coach said.
The Associated Press contributed to this report.