Edwin Jackson needed just 92 pitches in a 4-1 complete-game win over the Reds. (John McDonnell/THE WASHINGTON POST)

More than two hours before his first-ever Nationals Park start, right-hander Edwin Jackson stood at the bottom of the steps leading into the clubhouse. He paused in the tunnel, squared his shoulders and took a deep breath, his shoulders heaving. Then he threw a phantom pitch to no one and continued on his way.

Maybe he was calming his nerves prior to his debut appearance before Washington’s fans. Or maybe he was making one final dry run of the tweaked mechanics that Nationals coaches have been teaching him since he signed in the offseason.

Whichever it was, Jackson showed he’s a capable No. 4 starter and valuable addition to the Nationals’ rotation, striking out nine and allowing only one run in a complete-game 4-1 win over the Cincinnati Reds.

For much of his 10-year career, Jackson has been a nomad: He has yet to spend two full seasons with a team. But by signing him to a one-year, $11 million contract, the Nationals saw a durable starter with a blazing fastball. He has thrown more than 180 innings the past four seasons.

Saturday’s gem was Jackson’s fifth complete game of his career, and the first for the team this season. He needed only 92 pitches.

Soon after Jackson reached a deal with Washington, Nationals General Manager Mike Rizzo discussed tweaking the pitcher’s windup. And during spring training, Nationals coaches did just that. They felt he was slightly less effective from the wind-up than from the stretch because he slightly showing the ball to batters.

In his first start of the season on Monday, Jackson allowed three runs on four hits over five innings and didn’t earn a decision. But on Saturday before an announced crowd of 35,489, he was a calmer, quicker and more efficient version of that.

The Reds scored first off Jackson in the second inning, using a single by Drew Stubbs to plate Miguel Cairo, who had reached on a one-out double. The Nationals tied the score the same inning when Jesus Flores singled to right field to score Jayson Werth.

The Nationals took the lead for good in the third inning. Danny Espinosa drew his team-leading eighth walk and Ryan Zimmerman followed with a single to the left side. Then, on the third pitch of the at bat, Adam LaRoche lined a two-run double to right field.

Slowly the Nationals were beginning to look – almost – as they were envisioned. Rick Ankiel, back from a tight quadriceps muscle that landed him on the 15-day disabled list to begin the season, started his first game. LaRoche and Zimmerman, both slowed by injuries last season, were on the field and playing well in unison – as they did in the third inning when LaRoche brilliantly saved Zimmerman from an error on a low throw after a high-bouncing chop.

After his only blemish, Jackson cruised. His fastball was electric. (Even late in eighth inning, he was hitting 95 mph.) His slider and curveball were throwing off batters. From the second inning to the seventh, he retired 16 straight batters. He needed only 66 pitches to get through seven innings.

And even after he issued a walk to start the eighth inning and reliever Tyler Clippard started warming in the bullpen, Jackson looked more resolved. He struck out the next three batters: two on a slider and one on a fastball.

When he came out to bat in the bottom of the eighth inning, the crowd cheered Jackson. He could finish what he had started – and he did.