Jose Reyes smiles during a workout on his first day...

Jose Reyes smiles during a workout on his first day back at the Mets spring training complex in Port St. Lucie, Fla. after missing 20 days due to a hyperactive thyroid. (Mar. 24, 2010) Credit: AP

PORT ST. LUCIE, Fla. - Shortly after yesterday's arrival, Jose Reyes retreated to a back field with Jerry Manuel, who slapped ground balls to him at shortstop. On the ninth one, Reyes rifled a throw to first, stood up and smiled.

"Oh man," Reyes yelled. "I'm ready, bro'!"

It was the type of reaction everyone around the Mets had anticipated - and feared. But Reyes was only joking. Later, after his hourlong workout was finished, Reyes said all the right things and promised to be patient.

"I feel better than I expected," Reyes said. "I caught ground balls, my hitting was good, my running was good. I didn't run full speed because it's my first day and I don't want to blow one of my hamstrings because that's going to be a big problem. So I just take it easy on that. Let's see what happens."

Reyes looked identical to the player who left the Mets back on March 5 when he returned Wednesday to the spring-training complex. Whatever effect the elevated thyroid levels had on him was not discernible from the outside.

Even when Reyes suited up and joined the rest of the Mets for conditioning drills, he was the same, finishing a few steps ahead of his teammates every time. But Reyes will be on his own program, under close supervision, until the Mets decide he will be ready to rejoin the lineup for a Grapefruit League game.

Although that date has not been determined, Reyes cleared his first hurdle by surviving his first hour back on a baseball field. He took batting practice, starting with soft tosses from hitting coach Howard Johnson, and then regular swings, but fewer than usual.

Afterward, Reyes did his usual agility drills, gliding through cones spaced about 90 feet apart in the outfield. Reyes appeared to be a little winded - he was coming off nearly three weeks during which he spent much of his time on his couch watching movies - but he said he was fine. The Mets, however, will be watching him closely as they chart his progress.

"It's not only what he says," general manager Omar Minaya said. "It's what we see."

As for Opening Day, which is April 5 at Citi Field, neither Reyes nor anyone else involved with the Mets could predict whether he would be in the lineup against the Marlins. Not after his first day back.

"I don't know that," Minaya said. "The only way to find that out is to see how he responds on a day-to-day basis. We want him for the long season - that's the focus."

Reyes toed the company line as well. He was curious to see how he would feel the following day and, probably at the Mets' urging, exercised patience when asked if he'd be ready to play Opening Day.

"Right now I just try to take it one day at a time," Reyes said. "So I went out and try to work as hard as I can to try to get ready as soon as possible. Of course I'm going to be anxious. But I don't want to put a date on it because I spent like 20 days not able to do anything, so I just have to get ready first and see what happens."

Even with Reyes back in camp, he is under strict medical orders. He must watch his diet - absolutely no seafood - and his thyroid levels still will be tested weekly. Reyes said the doctors told him it was a virus that caused his hyperactive thyroid and he was assured it would go away without medication.

Despite the positive diagnosis, Reyes said he "went crazy" when he heard that it could take up to eight weeks for the levels to go down. That's why Reyes was thrilled when trainer Ray Ramirez called him Tuesday and told him he could rejoin the team. At first, though, Reyes was nervous when he saw Ramirez's name pop up on his phone.

"I say, 'Oh my God,' " Reyes said. "Every time he calls me I go like this because I never get good news."

This time was different. And now that Reyes is with the Mets again, there was a positive vibe throughout the complex Wednesday. He was missed.

"His smile, his energy," Manuel said. "I think that's huge for us to have him back, even in the dugout."