Daisuke Matsuzaka started a Ni-gun game against Orix at Tama Home Stadium Chikugo on September 10. He was supposed to pitch five inning and throw about eighty pitches, but instead left after three shutout innings and fifty-eight pitches. He struggled with his control and walked/hit seven. He topped out at 143km/h.
Matsuzaka may have tweaked his right leg because he seemed bothered by it in the third innin/g.
[UPDATE 9/11 @ 12:56am]
Matsuzaka left the game with tightness in his right buttock. He was bothered by the tightness before the start of the game. He may not have to miss his next start, if the tightness goes away within a day or two.
Source: Tokyo Sports 9/10/2016
[UPDATE 9/11 @ 4:12pm]
According to Sponichi, Matsuzaka may have hurt (or aggravated) his right buttock when he went to cover first base in the third inning.
Source: Sponichi 9/11/2016
[UPDATE 9/11 @ 8:50pm]
Matsuzaka worked out at the Ni-gun facilities in Chikugo today. He played catch for about ten minutes to check on his right leg. A trainer told reporters that their was still some tightness in the buttock. Whether he makes his next outing on September 17 (Ni-gun Chunichi at Nagoya Stadium) will depend on how he is feeling over the next couple of days.
Source: Daily Sports 9/11/2016