PITTSBURGH — Jeff Samardzija began the season as the Chicago Cubs’ No. 1 starter practically by default thanks to injuries to veterans Matt Garza and Scott Baker.

Don’t expect the quickly improving Samardzija to give up the spot anytime soon.

The lanky right-hander allowed just two hits and struck out nine over eight nearly flawless innings as the Cubs held off the Pittsburgh Pirates 3-1 on Monday for their first opening day victory in four years.

“He stuck to his game plan,” Chicago manager Dale Sveum said. “That was probably as good of a game that he’s pitched in his starting career.”

Samardzija’s only real issue came in the first, when a walk and an error put two runners on with nobody out. A fielder’s choice and two strikeouts later Samardzija was out of the jam. At one point he retired 14 straight batters, almost all of them on strikeouts or routine groundballs.

“When they’re making plays behind you it gives you the confidence to really kind of make stuff up out there, keep the ball down in the zone and you know they’re going to make some plays for me like they did all day for me,” Samardzija said.

And the Pirates were only too happy to oblige Samardzija as he worked both sides of the plate and kept the Pirates off-balance with a two-seam fastball clocked in the mid-90s and a changeup that didn’t break 80.

Pittsburgh only managed two balls out of the infield while Samardzija was on the hill as he improved to 4-0 in his short career against the Pirates.

“The last two times we’ve seen him, he’s been a beast out there,” Pittsburgh manager Clint Hurdle said. “He had command of everything out of his hand.”

Anthony Rizzo hit a two-run homer in the first and Wellington Castillo added an RBI double for the Cubs. Kyuji Fujikawa got the final out to earn a save in his major league debut after closer Carlos Marmol struggled.

A.J. Burnett, making the first opening day start of his lengthy career, gave up three runs on six hits in 5 2-3 innings, striking out 10. Pittsburgh however began a season of high expectations with a thud.

Burnett said it was an honor to get the call in the opener, but the 15-year veteran showed some nerves early. Castro singled with one out and Rizzo followed with a towering two-run shot to center field that landed on the concourse behind the seats for one of the longest homers in the park’s 13-year history.

The ball left the park so fast even center fielder Andrew McCutchen trotted only couple of steps before stopping.

Rizzo hit just .229 in spring training with just three extra base hits, but his blast gave the rebuilding Cubs an early shot of adrenaline.

“I don’t really remember the pitch or where I hit it or whatever,” Rizzo said.