MINNEAPOLIS -- Chicago Cubs right-hander Jake Arrieta just kept getting better Sunday against the Minnesota Twins.

His consistent improvement was bad news for a helpless Twins lineup, as Arrieta finished off his second career complete game shutout in an 8-0 Cubs victory against the Twins at Target Field.

Arrieta allowed just four hits and walked none, throwing 122 pitches for his team-leading seventh victory.

"Stuff was crisp throughout, got better as the game went on," Arrieta said. "I found a really good tempo and timing with my delivery."

Two of Minnesota's four hits came in the first inning.

Second baseman Brian Dozier singled to lead off the game but was out on a double play by left fielder Eddie Rosario. After a double by first baseman Joe Mauer, Arrieta got out of the inning by getting third baseman Trevor Plouffe to line out.

Arrieta committed a fielding error in the third and allowed a two-out single in the fourth before retiring 12 consecutive batters, allowing a single to Byron Buxton with two outs in the eighth.

"His stuff kept getting better," Cubs manager Joe Maddon said. "If he had been through a bunch of high-stress moments (removing him from the game) would've been a different story, but he was not."

Arrieta's stuff wasn't overpowering early. He struck out just one through the first four innings, but fanned three-in-a-row in the fifth and fanned another to start the sixth.

"Good pitching beats good hitting any day. I don't care if you're a hot team. What he did today would have shut anybody down," Twins right fielder Torii Hunter said. "He was locked in. He was poised. He wasn't even laboring in the ninth. I was looking for him to take a deep breath or something, take his hat off and wipe his head."

Despite the great performance from Arrieta, the Twins were in the game until the eighth. A sacrifice fly by shortstop Starlin Castro in the third inning and a solo home run in the fifth by Anthony Rizzo gave the Cubs a 2-0 lead through the middle innings.

But a six-run eighth, capped by a grand slam by Cubs center fielder Dexter Fowler, broke the game wide open. It was the second slam of Fowler's career.

Designated hitter Kyle Schwarber started the scoring in the eighth with a two-run single to left.

"We pulled through in the latter part of the game," Maddon said. "For (Fowler) to be able to do that, I hope there's a carryover for him."

Rizzo's homer was his third of the series. He had two hits apiece in each of the three games here. It was the first time a Cub had three homers in a three-game series since last August.

"Just staying within myself," Rizzo said. "I was just trying to put the bat on the ball, nothing more."

For the Twins, the sagging offensive output has become a disappointing trend. It was the 13th time this month (20 games) Minnesota scored two runs or fewer. It was the sixth time this season the Twins were held without a run.

"(The first inning) was our best chance all day," Twins manager Paul Molitor said. "We got a little tentative as the game went on, but (Arrieta) pitched real well."

Twins right-hander Kyle Gibson took the loss, allowing two runs on six hits and three walks over five innings. It snapped a five-game streak of consecutive quality starts by Twins pitchers.

NOTES: Cubs C/DH Kyle Schwarber was optioned to Triple-A Iowa following the game. Schwarber hit .364 with a homer, a triple and six RBIs in six games. ... Twins RHP Ervin Santana tossed 5 2/3 innings at Triple-A Rochester on Saturday as he readies to return from an 80-game suspension for PED usage. Santana is set to return to the bigs on July 5. ... The Cubs return home on Monday to open a three-game series with the Los Angeles Dodgers at Wrigley Field. ... The Twins open a three-game series with the Chicago White Sox on Monday at Target Field.