DAVIE, Fla. -- Miami Dolphins quarterback Trent Green flew to Kansas City for medical consultations and was optimistic about the recovery from his second severe concussion in 13 months.

"He went through some tests this morning, and he told me that it's very encouraging," coach Cam Cameron said Wednesday. "He's in Kansas City, dealing with the people he dealt with last year so they can make a direct comparison."

"He's really upbeat," Cameron said. "That's what makes those guys who they are -- they're competitors. They can't imagine not playing. With that being said, we've got to let this thing play out."

The 37-year-old Green was knocked unconscious with a Grade III concussion, the most severe, in Sunday's loss at Houston. A concussion in the 2006 opener with the Kansas City Chiefs sidelined Green for eight games, and he considered retirement before deciding to return this year.

The loss of Green moved rookie John Beck up one spot on the depth chart. He becomes the backup to Cleo Lemon, who will make his second NFL start Sunday at Cleveland.

"John's one play away at this point," Cameron said. "He's one play closer than he was before."

As the first quarterback drafted in the first or second round by the Dolphins since Dan Marino, Beck is widely considered their quarterback of the future.

He likes to fish, whether it's for trout in a stream in the Rockies, or for bass in the lake behind his house in South Florida. That makes it easier for him to endure the wait for his NFL debut.

"If you enjoy fishing, you have to be a pretty patient person," Beck said. "But I'm also kind of an anxious person -- not as far as nervousness, but just being excited for when the opportunity does come."

Green will likely be sidelined several weeks at least, forcing the Dolphins (0-5) to rely on Lemon or Beck. This week, Cameron opted for the inexperienced veteran rather than the untested rookie.

"We're not in a position right now where we're saying, 'Let's start playing John Beck just because he's a rookie,"' Cameron said. "We're going to play the guy that gives us the best chance to win today."

Receiver Marty Booker took snaps in practice and will be the Dolphins' emergency third quarterback this week.

There's speculation the Dolphins will give Beck his shot after their bye week in early November, allowing him two weeks to take practice snaps as the No. 1 quarterback.

By then, Miami could be 0-8 and headed for a high draft pick next April. Giving Beck a tryout would help them decide whether to acquire another quarterback in 2008.

Another argument for playing him is because Beck served a church mission in Portugal before beginning his college career at Brigham Young, he's a 26-year-old rookie and more mature than the typical first-year quarterback.

But Beck is content to wait, and said his grooming for the No. 1 job is incomplete.

"You always want to feel ready," he said. "You always want to be the guy. But the coaches know best. They've been in the NFL a lot longer than I have. I feel like I've progressed. I have a whole lot more I can learn, and a whole lot more I can do better."

Coincidentally, the backup quarterback on the opposing sideline Sunday will be Brady Quinn, widely expected to be drafted in the first round by the Dolphins last April. Miami instead selected receiver Ted Ginn Jr., which prompted fans at a team draft party to boo Cameron.

Quinn slipped to Cleveland, and the Dolphins took Beck in the second round. Alas, instead of a Beck-Quinn showdown Sunday, it'll be Lemon vs. Derek Anderson.

Lemon's only start came in the final game last season, when he threw for 210 yards and one score in a loss to Indianapolis. He replaced the injured Green in the first quarter at Houston and threw for 154 yards, but failed to get the offense into the end zone.

The climb to a starting job has been a long one for Lemon, who played in the Arena League and was on San Diego's practice squad. He has thrown only 95 passes in four NFL seasons, but said he's ready to be No. 1.

"I have always prepared myself to be successful in life," he said. "I never think negatively, so I am always prepared to be successful. When your number is called, you have to be prepared to take advantage of the opportunity."

Copyright 2007 by The Associated Press