BOSTON -- If Daisuke Matsuzaka could take back one thing on Saturday, it would be his lead-off walk to Bryce Harper on four pitches in the top of the fourth.
That walk led to a Ryan Zimmerman single, a Michael Morse RBI ground-rule double, and an Ian Desmond two-run single.
A lead-off walk quickly turned into a three-run inning for the Washington Nationals, and that -- combined with an Adam LaRoche solo home run in the top of the second -- would be all they needed at Fenway Park on Saturday, defeating the Red Sox 4-2.
Matsuzaka picked up the loss in his first Major League start since May of last season. His recovery from Tommy John surgery last June set up him for a rehab assignment in the minors, and then lined him up for Saturday's season-debut against the Nationals.
He said after the loss that it was the most nervous he's been since coming to Boston from Japan.
"When I was first told by Bobby that I would be starting today's game, every time I thought about the game, I would become a little nervous," said Matsuzaka through his translator. "The preparation aspect, too, I thought the nerves coming off -- especially during the bullpen -- was probably the most nervous I've been during my time here in Boston."
Those nerves didn't seem to phase Matsuzaka too much, as he began the day with a 1-2-3 inning in the top of the first, while striking out two batters, each with a filthy slider.
And even after LaRoche hit a solo home run to begin the second inning, which gave Washington a 1-0 lead, Matsuzaka didn't seem rattled, and came right back with another strikeout and two more quick outs to end the inning.
Matsuzaka then went into the top of the third and put together another 1-2-3 inning, while racking up two more strikeouts. He finished the day with eight strikeouts, five of which came in the first three innings.
But it was that one walk that will haunt him.
"The biggest difference I think today was the consistency of my velocity, and the command of all my pitches," said Matsuzaka. "But what hurt me the most today was that one walk."
The Red Sox offense was shut down on Saturday. So that didn't help matters. And during any usual Matsuzaka start, the Red Sox will take only one walk from him.
And eight strikeouts in five innings to go along with that one walk? Yeah, they'll take that too.
"I didn't like the four runs, I didn't like the four balls to Harper in that one at-bat," said Valentine. "Other than that, I liked what I saw. I thought he threw a lot of strikes. He threw all of his pitches. He had good off-speed stuff, some pretty good command of his fastball, except for that one at-bat. He had it moving both ways. Kelly Shoppach thought it was OK. From the side, it looked OK.
"Usable. If we can get him to build on that -- eight strikeouts in five innings -- it's pretty good."
Matsuzaka was only "usable" for five innings on Saturday. Before the game, Valentine said that he would check in with Matsuzaka after each inning. And after the fourth -- in which he allowed three runs -- Valentine told him that the fifth inning would be his last.
So he went out in the fifth and allowed a ground-rule double to lead off the inning. He then retired the next three batters, including two more strikeouts, finishing his night by getting phenom Bryce Harper to look at an inning-ending called strike three.
Matsuzaka said afterwards that he wanted to go more than five innings.
"When I came off the mound, I came back to the bench after the fourth inning, and I was told that the next inning would be my last," said Matsuzaka. "But coming off after the fifth, I felt like I wanted to go out there for another inning."
Matsuzaka has a lot to build on. But after his first start of the season, he'll be building with confidence.
"Every time you pitch, you want to give your team a chance to win," said Matsuzaka. "And, losing today was very disappointing. But I think I did leave some positives for my next start. And I definitely think I pitched better than I had been during my rehab assignment."