FORT MYERS, Fla. - Tyler Thornburg returned to the mound on Sunday for the first time since thoracic outlet syndrome surgery last summer.

He threw 10 fastballs as a warm up to first full bullpen session.

The right-hander fired 20 crisp fastballs into the mitt of Christian Vazquez on Wednesday. Vazquez hollered in delight at the end of Thornburg's session.

Thornburg had the surgery to repair nerves and ligaments in his neck and shoulder in June. He began throwing again in October, gradually building up distance and endurance. Everything led up to Wednesday's session.

"Pretty darn good," Thornburg said after the session when asked how it felt. "It's one of those feelings you realize you miss a lot once you don't do it for a year I guess."

Thornburg expects to have two days off from throwing and then throw another bullpen to see how he responds to the session on Wednesday. Thornburg's progess will depend on how he feels after each outing but after three or four bullpen sessions, he could advance to throwing live batting practice.

The 29-year-old said he feels better now than he did in 2016 when he had his best career season, posting a 2.15 ERA and 12.1 K/9 over 67 appearances in Milwaukee. At that time, he was still navigating intermittent pain before it escalated to the need for surgery.

"(In) '16 felt like I had to do a bunch of stuff to get ready on a daily basis and it was pretty much a day-to-day thing but I found ways to deal with it," Thornburg said. "That's one thing that makes me, I don't know, giddy to get on the mound again and giddy to get into games is because, you know, if I never have those issues, like how good I feel I can be."

Thornburg said he threw at about 80 percent effort on Wednesday as he eases himself back into action, but he felt he could have kept throwing.

"Just the fact I finished this bullpen and felt like I could throw way more, felt like I could have thrown harder, and just the fact it doesn't feel tired, it doesn't feel like it's going to be overly sore or anything tomorrow is probably a better feeling than even throwing with location I was throwing in my bullpen today," Thornburg said. "How it's feeling is the No. 1 goal, so I'm really excited about where it is and how it feels right now."

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