Kazmir, who pitched only once last year after Aug. 22 because of thoracic inflammation, said he still needs to iron out bad habits, but said physically he felt fine.
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Ryu and Kazmir are part of a large group of starters jockeying for slots behind Clayton Kershaw, Rich Hill and Kenta Maeda. Julio Urias will be the fourth starter at some point, but the club wants to ration his innings early. So initially there will be one or two starting jobs available for Ryu, Kazmir, Brandon McCarthy, Alex Wood, Brock Stewart and Ross Stripling to fight for.
Ryu, 30 next month, went 28-15 in his first two seasons after coming over from Korea. He said he faces some of the same challenges now that he did when he arrived.
"I only pitched one game the last couple of years so there are question marks around my name, just like 2013 when I first got to the Dodgers," said Ryu. "There definitely are things I need to prove to the organization to be in the rotation.
"Last year I might have doubted myself and that might have showed through [in a lack of arm extension]. During the offseason and everything I put into it, I feel confident in my ability and body condition."
Ryu left chilly Korea for warmer Okinawa with a physical trainer in early January and has been throwing three bullpen sessions a week for five weeks, putting him on schedule to be in the first pair to throw batting practice.
"As a pitcher I definitely want to be in starting rotation from day one," he said. "And from the looks of it, I have a lot of confidence I can make it."
Yasmani Grandal, who caught Ryu, said his improved health was obvious.
"The fact that he was able to spot and mix his pitches was a huge improvement from last year," said Grandal. "He's not thinking about what will happen if I let this pitch go."
Kazmir -- a 10-game winner last year after signing to help fill holes created by Ryu's injury and Zack Greinke's departure -- followed the 25 pitches with a handful more without a batter as he continued tweaking his mechanics.
"The first 10 to 15 felt perfect, then I started to get longer and I had a good session after," said Kazmir, 33. "I threw like 80-something pitches in a session before I came in here. For me, it's just getting reps on the mound to create that feel. I'm finally doing it right and it feels like I'm quicker."