Keller grabbed his right knee after a tackle by D.J. Swearinger on an incomplete pass.
Signed as a free agent over the offseason following five seasons with the New York Jets, Keller was expected to have a significant role in the passing game with the Dolphins also adding speedy outside threat Mike Wallace. The goal was to have Keller and wide receiver Brian Hartline work the underneath routes with Wallace stretching the field.
The Dolphins will now turn to a trio of young tight ends - Charles Clay, Michael Egnew and Dion Sims - in an attempt to fill the void. With roster cuts looming, the Dolphins could also seek to add a veteran to the mix.
Clay has displayed versatility as a blocker and receiver, Egnew was a significant disappointment as a rookie last season and Sims is a big, athletic rookie out of Michigan State.
"Dustin brought a lot to the table for us," quarterback Ryan Tannehill said after Saturday's game. "He's a great player and it's a tough situation. But at the end of the day we have to have somebody step up and play in his shoes. We have a good tight end room with Egnew, Clay, Dion, and those guys are going to have to step up and fill the void. I think we have the guys in the room to (succeed)."
Clay has been listed as a fullback/tight end on the roster, while Egnew and Sims are big, speedy targets who still need to refine their route-running.
"We have other guys that have caught the ball down the middle," head coach Joe Philbin said Saturday. "We've got some big targets. Egnew is a big man. Dion Sims is a big man. Clay has caught the ball down the middle before. We'll adjust."
Egnew was was inactive for all but two games last season despite being a third-round pick. However, he has displayed improvement this year and has five catches through two preseason games.
Sims is a fourth-round pick who has impressed throughout the offseason program and training camp.
"Definitely, I'm ready to go," he said. "I've been ready to go since I first stepped foot there at the facility."
While all three have displayed the ability to catch passes over the middle, they're also relatively inexperienced players - each had a penalty called against him Saturday.
"Early in the game we had three penalties out of the three tight ends, which wasn't good," Philbin said. "But I thought they settled in and played better as the game went on. I like the guys we have. Again, we have to see what happens. It's very early in this whole process. We'll take a look at what we have, what our options might be."
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