KANSAS CITY, Mo. (AP) -- Zack Greinke is developing into a strikeout pitcher at age 24.
"When there are runners on base, that's the only time I really try to strike anybody out, at least from the first pitch," Greinke said. "I threw a lot of quality pitches and got ahead in the count and they chased them. A lot of strikeouts weren't strikes."
The Royals have won four straight and nine of 10, all against National League clubs. Their 11-3 record is the best in interleague play.
The game included a frightening moment in the bottom of the second inning when plate umpire Brian O'Nora was hit in the head by a shattered piece of Miguel Olivo's broken maple bat.
With blood streaming down his face, O'Nora rushed to Kansas City's dugout, where Jose Guillen quickly covered the umpire's head with a towel.
"I turned around and saw him running off the field and then I saw he was bleeding -- blood everywhere," Rockies catcher Yorvit Torrealba said. "Once I saw the blood, it almost made me sick. He's a really nice guy and hopefully he's doing well."
O'Nora came out of the game and was treated by Kansas City trainer Nick Swartz. The Royals later announced that O'Nora had a small cut on his forehead and was taken to St. Luke's Hospital for further evaluation.
Earlier in the day, Major League Baseball said it will start testing bats following Tuesday's meeting of a player-management safety committee, but the sport made no decision on the contentious issue of banning maple models.
"They are very, very dangerous. I'm surprised that this is the first incident we've seen," Royals manager Trey Hillman said. "It could have been worse, a lot worse. It looked a lot worse than it was. My understanding is that he is OK."
After O'Nora was hurt, both teams left the field and the game was delayed for 13 minutes before resuming with three umpires. Paul Nauert, who began the night as the first base umpire, moved behind the plate.
"I feel so bad for the umpire," Olivo said. "I saw the blood come out and they came out and put a towel on his head. I just worried a little bit."
Greinke (7-4) was unfazed, scattering nine hits and walking none in six innings. His other 10-strikeout game was Sept. 20, 2007, against the Chicago White Sox. In his past three starts, Greinke has allowed four earned runs and 14 hits in 20 innings, while striking out 22.
"He was very effective," Hillman said. "It's good to have guys missing bats. Especially against this club that can slug it like they can, you don't like seeing the ball put in play a whole lot. You know Zack has it in there because he is power."
Gordon's ninth home run with Mike Aviles aboard in the seventh gave the Royals a four-run cushion. Aviles went 2-for-3 with a walk, an RBI and two runs and is hitting .352 since his May 29 promotion from the minors.
The Royals sent eight batters to the plate in a three-run fifth to chase left-hander Jorge De La Rosa (2-4) and take a 4-3 lead. John Buck led off the inning with a double and scored on Ross Gload's single.
De La Rosa, who was in the Royals' rotation the past two seasons and was traded to the Rockies on April 30, retired the first 10 Royals he faced, striking out four before walking Aviles, who advanced to third on a two-base throwing error by second baseman Clint Barmes. Olivo's two-out single scored Aviles.
De La Rosa departed after 4 2/3 innings, yielding four runs, two earned, on five hits and three walks.
"Out of the chute, it was very clean," Rockies manager Clint Hurdle said. "The first 10 hitters he faced he retired. Maybe he got a little quick in the fourth inning. It seemed like he stopped throwing the slider. It was almost all fastball, changeup after that. Two unearned runs, we didn't help him defensively."
There was a bizarre twist in the ninth when Royals reliever Ramon Ramirez threw two pitches behind Torrealba, his former batterymate with the Rockies. The umpires issued a warning to both benches. Ramirez said his hands were sweaty and the ball "slipped."
"My complaint is we've seen guys get thrown out after two errant pitches like that," Hurdle said.
Royals 2B Mark Grudzielanek missed his third straight game with a sore lower back. ... Rockies DH Jeff Baker went 0-for-4 and struck out three times, snapping his nine-game hitting streak. ... DeJesus extended his hitting streak to 10 games.