Mariners 1, Royals 0: Hisashi Iwakuma pitched eight shutout innings and Corey Hart had a run-scoring single as host Seattle defeated Kansas City.Iwakuma (2-0) struck out seven and gave up just four hits in his second outing of the season. Fernando Rodney worked out of a self-induced jam in the ninth for his 10th save as the Mariners won for the sixth time in seven games.Royals starter Danny Duffy (1-3) also pitched well, allowing one run and two hits in six innings. Eric Hosmer reached base three times and had two of Kansas City's four hits.Mike Zunino led off the third inning with a double and was sacrificed to third by Michael Saunders. Duffy struck out Stefen Romero and intentionally walked Robinson Cano before Hart delivered a single to left-center field to score Zunino.Iwakuma, who missed the first month of the season due to a finger injury, didn't walk anybody and 61 of his 93 pitches went for strikes. Rodney walked Alcides Escobar and Hosmer in the ninth and struck out Billy Butler for the second out and induced Salvador Perez to hit into a fielder's choice to end it.GAME NOTEBOOK: Iwakuma is 7-0 against American League Central opponents and hasn't allowed a run in his last 48 2/3 innings against teams in that division. … Mariners OF Logan Morrison (hamstring) had a setback in his recovery and it is uncertain when he will be ready to go on a minor-league rehab stint. … Royals 2B Omar Infante (back) was held out of the lineup for the second straight game.