Eddie Rosario was on deck Sunday as Brian Dozier batted — for the second time — in the first inning. Rosario suddenly walked over to hitting coach James Rowson, who was standing behind the rail front of the dugout.

The two exchanged a few words. Rosario patted him on the shoulder and returned to the on-deck area.

"He was just refreshing himself if the ball was going to cut, be straight, or sink," Rowson said. "So he was worried about pitch movement at that time, trying to remind himself of what it was."

Dozier walked to load the bases, bringing Rosario up. He fell behind 0-2, but Diamondbacks righthander Braden Shipley threw him a belt-high fastball that he was able to crank on.

Rosario drove the ball over the right-field wall for a grand slam, one that topped off the Twins' nine-run first inning, led them to a 12-5 win over the Diamondbacks and was the latest example of a team on a tear at the plate.

"That goes to show you what he has been doing and why he's been so good," Rowson said. "He's been prepared every at-bat."

The Twins head into the Windy City for a five-game series against the White Sox on a roll. They swept Arizona, have won four straight and 11 of their past 14.

The nine-run first was the third time in club history they have scored that many in a first inning. So the special inning allowed righthander Bartolo Colon to achieve a special feat. Colon gave up four runs over six innings — including three solo home runs — to improve to 5-10. But Arizona was the only team Colon had not beaten in his 20-year career. Now he has at least one win against every major league team, one of 18 pitchers to do so.

"It means a lot. It means a lot to my career," Colon said. "Last year, there were two clubs I hadn't beaten, the Cubs and Arizona. And I beat the Cubs in New York and now this means a lot to me.

"Now I haven't won in two stadiums, so that is the next goal."

Rosario has been a regular at early batting practice. So has Miguel Sano, Byron Buxton, Jorge Polanco and Max Kepler. One reason the Twins offense has taken off lately is that their work is paying off.

Kepler scored on Rosario's slam. But he reached base after a nine-pitch at-bat against lefthander T.J. McFarland. Kepler fouled off six pitches before holding up on a check swing, then blasting a two-run double to center. He entered the game batting .135 against lefties.

"I thought Kepler's at-bat was one of the better at-bats we have had all year," Twins manager Paul Molitor said, "given the fact he has struggled against lefties."

Polanco had an RBI single on Sunday and is batting .397 in August. Buxton ran his career-high hitting streak to 10 games, during which he's batting .405. Sano hit two homers on Friday before landing on the disabled list Sunday because of a stress reaction in his tibia.

The Twins will have to make up for Sano's loss. Right now, they are swinging well enough to. They began the day leading the AL in batting average since Aug. 6 and were second in runs scored and on-base percentage. And they batted .355 against the Diamondbacks, who are in the NL wild-card race.

"To sweep a series at this time of year, when you are still in the hunt, it feels pretty good," Molitor said. "Against a good team over there. In bad uniforms."