Watch Now: MLB Key Injuries Heading Into Restart (4:54)

New York Yankees right-hander Masahiro Tanaka was diagnosed with a mild concussion after being struck in the head by a line drive off the bat of teammate Giancarlo Stanton on Saturday. On Sunday, Tanaka was back at Yankee Stadium and showing good progress. 

"He came in around noon today and was in really good spirits," Yankees manager Aaron Boone said Sunday (via ESPN's Marly Rivera). "Got a really good night's 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 ... [was] in good spirits popping around today, so I think at this point we're really encouraged."

Tanaka, who had been throwing a simulated game at the time, had to be helped off the field following Saturday's incident. He stayed down for several minutes before being assisted to the clubhouse by two trainers.

The whole scene was captured and broadcast on YES Network as part of its coverage of the start of the Yankees' second camp. Though we would advise against it, you can click here to watch it for yourself.

The Yankees tweeted an update on Tanaka's status shortly after, noting that he was "alert, responsive and walking under his own power," and that he was being sent to "NewYork-Presbyterian Hospital for further evaluation and testing." Tanaka was released from the hospital on Saturday evening.

Tanaka, 31, is set to enter his seventh season with the Yankees. In his first six years, he averaged 27 starts per season and compiled a 113 ERA+ and 4.74 strikeout-to-walk ratio. Last year, he made his second career All-Star Game and led the Yankees in innings pitched.

Stanton, who reacted in horror, has gone through a somewhat similar experience before. He was hit in the face by a Mike Fiers pitch in September 2014. He suffered multiple facial fractures and required stitches and dental work as a result.

The Yankees are reportedly scheduled to begin their season against the Washington Nationals on July 23. It's unclear whether that game will be played because of the state of the pandemic and the spread of COVID-19 across the country. Major League Baseball had originally planned on launching its 2020 season on March 26. The novel coronavirus forced the league to hit pause on those plans about two weeks prior, right along with the rest of the sports world.