Heap is dealing with tightness in his lower back, and Williams experienced twinges of pain in his right hamstring. Neither player practiced in the afternoon.
"My body is feeling good, so I’m just trying to be smart with what I’m doing," said Heap, who indicated he could return to practice as soon as today. "There isn’t anything, just being smart with my body. I’m just going to try to play it by ear."
Added offensive coordinator Cam Cameron: "We knew his back was tight. We kind of had a head’s up on both of those guys."
Like Heap, Williams said he doesn’t regard the injury as serious.
"I’m just being careful," Williams said. "It’s nothing that’s going to keep me out."
The Ravens can’t afford to suffer long-term injuries at tight end or wide receiver with L.J. Smith still working his way back from a hamstring injury and wide receiver Mark Clayton sidelined for at least half the preseason with a strained hamstring.
Kelley Washington and Justin Harper ran with the first-team offense in Williams’ absence.
Improved durability has been a major emphasis for Williams after missing the majority of last season and undergoing surgery on his Achilles tendon and ankle.
"To Demetrius’ credit, he fought through that," Cameron said. "We wanted to be smart with him. Obviously, we prefer not to push a guy to an injury point. We got him out right in time, I think."
Also not practicing: linebackers Terrell Suggs (left heel, Achilles tendon) and Brendon Ayanbadejo (toe sprain), wide receivers Clayton (left hamstring), Thomas White (hamstring) and Biren Ealy (groin), offensive tackle Stefan Rodgers (calf, heel), defensive tackle Lamar Divens (hip flexor) and cornerback Samari Rolle (neck).
Rolle remains on the physically unable to perform list.
Plus, offensive tackle Jared Gaither (left trapezius) and wide receiver Ernie Wheelwright (shoulder) didn’t practice following the morning session.
Defensive end Trevor Pryce (foot) left the afternoon practice early for treatment.
PENDING DEBUT: The Ravens are eagerly awaiting rookie offensive tackle Michael Oher’s initial NFL preseason game Thursday night against the Washington Redskins.
The first-round draft pick will start at right offensive tackle, and he’s being groomed to lock down the position on a permanent basis.
“I want to see him play with technique,” Cameron said. “I’m going to talk to him about that. I want him to be aggressive, and we’re going to put him in positions to be aggressive. I think that’s what you have to do with a young offensive player.
“If they’re aggressive and miss, they grow. Then, we can teach them when to not be over-aggressive. We’re going to put his hand on the ground, get his feet off the ground and have him get after people.”
MAKING AN IMPRESSION: Undrafted rookie inside linebacker Dannell Ellerbe continues to line up with the first-team defense next to All-Pro middle linebacker Ray Lewis.
"It feels great," Ellerbe said. "Everyone is out there communicating. I’m just out there having fun."
Ellerbe, who was given a $2,000 signing bonus as a free agent out of the University of Georgia, is emerging as someone that the coaching staff is considering for the 53-man roster.
“Yeah, a lot of it is going to be how he plays in these upcoming four games,” defensive coordinator Greg Mattison said. “But he has really, really improved, and we knew that right away when he got there that he had ability.
“He shows to be a very intelligent player, because to be a linebacker in our scheme you have to have some intelligence. He’s picked things up. He runs to the ball real well. He’s athletic.”
SLEEPER: The Ravens are high on reserve running back Jalen Parmale, who rushed for 27 yards on two carries last season.
Cameron regards the former Miami Dolphins’ practice squad back as a hidden talent.
“My gut feeling is that he will really shine in these preseason games,” Cameron said. “My gut feeling is he can break tackles. I have a feeling that this guy is powerful.
“He’s got some explosion. He’s got some speed. I’ll be very surprised if he doesn’t really play well when the lights come on.”
QUOTABLE: Running back Ray Rice on the sweltering weather: “Excuse the heat. Mother Nature came down on us today.”
QUICK HITS: Cameron said that the Ravens wouldn’t hesitate to bring in a veteran wide receiver because of concerns about absorbing the playbook. “We can bring anybody in at any point in time in the season as late as Wednesday that week and get them ready to play,” he said. “ That’s the risk and magic of this system, in the sense that a guy can learn the system quickly. Our system, the three-digit system, that’s what makes it good. If guys go down, guys can pick it up, the base offense, quickly. The rest, we just have the guy next to him tell him, ‘Just tell him what to do.’” … Mattison indicated that the Ravens won’t show much of their blitz package and will remain in a base defense against the Redskins for the most part. … All four of the Ravens’ preseason games will be broadcast on WBAL-TV. Three games will be simulcast on MASN with ESPN doing a national broadcast of the Ravens’ Aug. 24 Monday night game against the New York Jets.