"The Dolphins began preparing for their regular-season opener against the Buffalo Bills without franchise left tackle Jake Long.

Long, who suffered an injury to his left knee three plays into second quarter of the Sept. 2 exhibition loss at Dallas, sat out all of Monday's practice.

Long rode an exercise bike for a couple of minutes during the sessions. He appeared to walk without a limp, but wore a bulky brace on his left knee.

"It's an unfortunate circumstance," coach Tony Sparano said, defending his decision to play his starters in the exhibition season finale, which exposed them to injuries like the one Long suffered. "I'm not going to Monday-morning quarterback any of those decisions."

Sparano played his starters because he felt his team needed work.

During Monday's practice, second-year tackle Lydon Murtha filled in for Long with the first team. The team has three more practices and a walkthrough before Sunday's 1 p.m. road game against the Bills.

Sparano said Murtha had done enough in training camp to "keep our interest," earning himself a spot on the 53-man roster for now. But Sparano did point out the competition for backup tackle roles has improved.

"There's obviously a whole other step here for Lydon because he hasn't really played in a game really, not meaningful plays, anyway," Sparano said."