"I'm not here to be an Alge Crumpler replacement," Hartsock said after Wednesday's practice. "That's not something anybody can do. He's a special type player."
Each tight end will be playing against his former team when the Titans visit the Falcons in a preseason game Friday night.
The Falcons signed Hartsock, the former Titans starter, in March after releasing Crumpler. Tennessee quickly signed Crumpler, a four-time Pro Bowl player with Atlanta.
Crumpler had knee problems last year and missed two games, but he still had 42 catches for 444 yards and five touchdowns.
Hartsock has only 24 catches in 45 career games, including 12 receptions with the Titans last year in a shared role with Bo Scaife .
RAMS: Running back Steven Jackson ended his holdout while his agent continues negotiations for a new contract.
The 235-pound Jackson, a bruising runner and the centerpiece of the team's offense, is entering the final year of a five-year, $7 million deal he signed as a first-round pick in 2004.
BRONCOS: Five-time Pro Bowl center Tom Nalen is headed back to the operating table.
The 37-year-old Nalen will undergo another surgery on his left knee today, said coach Mike Shanaha n, who is holding out hope that his center will be ready for the season opener, Sept. 8.
EAGLES: Philadelphia wide receiver Kevin Curtis will have surgery today to repair a sports hernia and will likely miss the start of the regular season.
PANTHERS: Carolina released injured defensive tackle Ian Scott and signed receiver Sean Bailey , a former Georgia Bulldog.
JAGUARS: Competition between Clint Ingram and Justin Durant for the starting weakside linebacker spot continues, and it doesn't appear either has emerged as the clear cut No. 1.
BILLS: Quarterback Trent Edwards has a swollen bruise above his right kneecap, which forced him to miss practice Wednesday, a day after the Buffalo starter knocked knees in a collision with running back Marshawn Lynch .
SEAHAWKS: Quarterback Matt Hasselbeck did not practice again because of a stiff back, and he may also miss his second consecutive preseason game against San Diego.
RAVENS: Troy Smith will be Baltimore's starting quarterback for Saturday's preseason game against the St. Louis Rams, coach John Harbaugh said.
CHIEFS: Linebacker Demorrio Williams will likely miss the final two Kansas City preseason games with a broken bone in his right hand.