FORT MYERS, Fla. -- Right-hander Mike Pelfrey threw his first official bullpen session of Spring Training on Thursday, and said he plans on being ready for Opening Day despite undergoing Tommy John surgery last May.

Pelfrey, who signed a one-year deal worth $4 million this offseason after seven seasons with the Mets, is ahead of schedule in his rehab. He said he'll be treated like the rest of the pitchers this spring and that he's had no setbacks so far.

"If the season started tomorrow, I would have worked up to be ready at this point," Pelfrey said. "Realistically, after 7 1/2 months, I threw 90 pitches to hitters, so I could pitch [now]. They told me the other day, 'No restrictions. You're on the schedule with everybody else.' That's what I wanted."

Pelfrey began rehabbing his shoulder on Aug. 21 and finished his throwing program in December before taking three weeks off. He then started it back up again on Jan. 14.

He estimated he's already thrown off a mound 40 times since the surgery, including six times off the mound since mid-January. The Twins will continue to monitor his health and told him they plan to try to limit him to about 180 innings this season.

But Pelfrey said he could exceed that figure if he still feels healthy that late in the season. He's thrown more than 180 innings four times in his career, including throwing more than 200 innings in both 2008 and '10.

"My whole thing is if I get 160 and I'm tired, I'm going to end it and tell them I'm tired," Pelfrey said. "If I get to 180 and I feel good, I'm going to keep going. As long as I feel good, I'm going to keep doing it. I've busted my butt and worked my tail off to get back. I don't think if it gets to 200 it's going to be an issue. I've done it before."

Left-hander R. Perez invited to camp

FORT MYERS, Fla. -- The Twins signed left-hander Rafael Perez to a Minor League deal with an invitation to Major League Spring Training, the club announced on Thursday. Perez is set to arrive at the Lee County Sports Complex on Saturday.

Perez, 30, is coming off shoulder surgery in September and threw only 7 2/3 innings in 2012. But he's healthy, according to assistant general manager Rob Antony, and will be stretched out to start in Spring Training even though he's never started in the big leagues in 338 career appearances with the Indians.

"He liked the possibility of stretching out and possibly starting for us, which is what he did throughout the Minors," Antony said. "We just told him if he's one of our best starters, we're not going to turn a blind eye to anything. And if not, he's fine in the bullpen."

Before the shoulder injury, Perez was one of the better left-handed setup men in the American League, as he has a career 3.64 ERA with 268 strikeouts in 329 innings. He also posted a 3.25 ERA in 61 innings in '10 and a 3.00 ERA in 63 innings in '11.

Twins manager Ron Gardenhire was pleased with the signing, as he liked what he saw from Perez against his club. Perez has a career 1.89 ERA in 38 innings vs. Minnesota.

"He's filthy," Gardenhire said. "He's got great stuff. He's good out of the 'pen, but I like the idea of stretching him out, too. So we'll see what the best fit is for us and go from there. But he's a quality pitcher and a big league guy."

Gibson pushing forward despite innings limit

FORT MYERS, Fla. -- Although right-hander Kyle Gibson will have his innings total monitored throughout the season because he's coming off Tommy John surgery, he said Thursday he'll have no restrictions in Spring Training.

Gibson, who underwent the procedure in September 2011, threw his first bullpen session on Wednesday and reported no problems. And he'll be on the same schedule as the rest of the pitchers in camp moving forward.

"It was a good day yesterday," Gibson said. "It was fun. It was nice to be in that Spring Training mode and not be on the sidelines like I was last year. It was fun to be a part of it and made me feel like I'm part of the team again."

Gibson, who is ranked as the club's No. 4 overall prospect, according to MLB.com, is competing for the fifth spot in the rotation. It's his second time in big league camp, as he was a non-roster invite in 2011.

But he'll have his innings cut short this season, as the Twins are expected to limit him to about 130-140 innings. There are no plans to use him as a reliever initially to limit that total, but the Twins could decide to start him slowly at Triple-A Rochester before giving him his first call to the big leagues.

Gibson, though, said he has his eyes set on making Minnesota's rotation but knows it's far from a given.

"Everybody's goal is to break camp and even when I was a non-roster invite in 2011, that was my goal," Gibson said. "So it's definitely a goal. I know I have to work hard to reach that goal and it won't be given to me."

Rain doesn't wash away workouts

FORT MYERS, Fla. -- The Twins were forced to change their workout plans on Thursday because of rain, but manager Ron Gardenhire said everyone was still able to get their work in.

All 16 pitchers scheduled to throw bullpen sessions, including Mike Pelfrey, Liam Hendriks, Tim Wood, Anthony Slama and Trevor May, were able to throw off the mound near the club's Minor League complex.

The catchers -- and the other position players who are already in camp -- hit in the batting cages while pitchers were able to work on their bunting.

"We got just about everything done except for some of the fundamentals, like covering first base," Gardenhire said. "But we do that a lot so we're OK."