KANSAS CITY -- Finally.

The Royals’ mostly dormant offense in 2020 awoke on Thursday night with a fair share of pent-up anger. The unsuspecting victim was the Cubs’ pitching staff as every Kansas City hitter reached base at least once en route to a 13-2 victory at Kauffman Stadium.

The Royals snapped a six-game losing streak.

• Box score

Right-hander Brad Keller, making his first start of the season after being activated from the COVID-19 injured list, was the beneficiary. Keller threw five shutout innings, giving up three hits while striking out seven.

“We start with Keller and his presence on the mound. It’s big,” Royals manager Mike Matheny said. “It was a shot in the arm. You could feel it today, just having Brad being Brad out there.”

Meanwhile, the Royals pummeled Cubs starter Tyler Chatwood, who entered the game 2-0 with a 0.71 ERA. They chased him with one out in the third after racking up 11 hits and eight runs.

“That’s something we have been waiting to see,” Matheny said. “Every single guy contributed.”

The list of offensive highlights is a long one:

• Ryan O’Hearn snapped a 0-for-11 stretch with an RBI single in the first, then added an RBI double in the fifth.

• Whit Merrifield belted his fourth homer of the season, a two-run shot off the left-field foul pole. Merrifield stole a base and scored three times.

“I didn’t even know it hit the foul pole,” Merrifield said. “It looked like it would be fair to me. You never know with this park, so you just start running.”

• Adalberto Mondesi got the Royals’ six-run third going with an electrifying hustle double -- Statcast clocked his sprint speed at 30.5 ft/sec, which is classified as elite.

“I thought that was the spark, coming out of the box the way he did,” Matheny said. “That’s what he started, showing that kind of grit.”

Added Merrifield, “That guy brings spark with everything he does. He’s dynamic, electric. That’s one of the things he can do is hit a slow grounder past the infield and then it’s a double.”

• Salvador Perez had three hits, including two doubles and two RBIs.

• Jorge Soler had three hits, including his third home run.

• Maikel Franco doubled and homered, his third jack of the season.

• Rookie Nick Heath got his first big league hit, an RBI double in the third inning.

“I will send it home to my mom," said Heath about where that ball is headed. "I’m anxious to call her. I hope they put it up in the house somewhere. We have a lot of dogs running around, so one of them might get to it first.”

Keller was on top of his game from the start. He retired 10 of the first 12 hitters he faced, striking out five before finishing with 75 pitches (52 strikes) overall. And of course, he was grateful for the run support.

• Royals option three, reinstate Keller

“That was incredible,” Keller said. “We’ve been kind of grinding [to score] runs. To put up nine runs for me, it made it easier just to go out there and pump strikes.”

Keller’s four-seamer and sinker were just effective enough to set up his slider; he threw his slider 22 times and got eight swings and misses and two called strikes. Keller has tried hard to make his slider an effective swing-and-miss pitch.

“That was one thing we worked on in camp,” Keller said. “In the last two years, I kept bouncing the slider way short, especially with two strikes, and it just became kind of a waste pitch. One thing we really tried to work on is get it to the plate and make a swingable pitch.”