New York Yankees right-hander Masahiro Tanaka was back at Yankee Stadium on Sunday, a day after getting hit in the head by a line drive off the bat of Giancarlo Stanton.

Tanaka's quick return -- and relatively minor injuries -- is even more amazing when considering the speed at which that line drive was traveling when it hit Tanaka.

"That ball came back, I think they said 112 mph," Yankees lefty James Paxton told reporters Sunday.

The official diagnosis for Tanaka is a mild concussion, manager Aaron Boone told reporters.

"He came in around noon today and was in really good spirits," Boone said of Tanaka. "Got a really good night sleep; no loss of appetite. We're encouraged where he is and we'll take it day by day, but hopefully it's not something that'll take too long. Since he got to the hospital, he's pretty much been symptom free and feeling good ... (and was) in good spirits popping around today, so I think at this point we're really encouraged."

The scene was quite different a day earlier, as trainers and teammates immediately ran to the mound at Yankee Stadium to assist Tanaka, who remained on the ground for several minutes. The Japanese hurler was able to walk off the field with some assistance.

Tanaka, a two-time All-Star, posted an 11-9 record with a 4.45 ERA in 32 appearances (31 starts) last season with New York. The 31-year-old sports a 75-43 record with a 3.75 ERA in six seasons with the Yankees.

The other big news Sunday was Paxton, who threw live batting practice for the first time as he recovers from back surgery in February. He told reporters he is back to full health. The 31-year-old is entering his second season with New York. He posted a 15-6 record -- setting a career best for victories -- with a 3.82 ERA and 186 strikeouts in 150 2/3 innings last season.

On Sunday, he threw behind a protective screen during batting practice. That was an issue Saturday as Tanaka was not using the screen as pitchers have the option of using it or ditching it for live batting sessions.

"What happened yesterday was so scary. After seeing that happen, I just wanted to play it safe, especially first time out there," Paxton said of using the screen. "Luckily it doesn't happen very often, but I just wanted to play it safe the first time out. Next time it'll be more of a sim game setting, so the screen won't be out there. But, especially after yesterday, it was a conscious decision just to have it out there for safety."

"Obviously it's incredibly unfortunate what happened today," Boone said Saturday after Tanaka was hit, before later adding, "Unfortunately that's sometimes the risk that goes along with it. You do your best to protect guys, but you're not going to have a screen out there all the time."