Mariners 4, Royals 0: James Paxton struck out 10 in seven shutout innings and Justin Smoak smacked a three-run homer as host Seattle dealt a blow to Kansas City’s playoff hopes.

Paxton (3-0) gave up four hits and didn’t issue a walk in his fourth consecutive stellar start since reaching the majors. Yoervis Medina pitched a flawless eighth and Danny Farquhar allowed a ninth-inning single in a non-save situation.

The Royals dropped four games behind Cleveland for the American League’s second wild-card spot with five games to play. Kansas City and Seattle wrap up the three-game set on Wednesday before the Royals close the campaign with four road games against the Chicago White Sox.

Kendrys Morales went 3-for-4 and delivered a run-scoring single in the first inning for Seattle. In the fifth, Morales hit a two-out double and Franklin Gutierrez walked before Smoak sent a blast off Bruce Chen (8-4) over the left-field fence to increase the lead to four.

Chen allowed four runs and seven hits in five innings.

GAME NOTEBOOK: Paxton has struck out 21 and allowed only 15 hits in 24 major-league innings. … Royals DH Billy Butler was hitless in four at-bats and has gone 26 consecutive games without a homer. … Seattle 2B Nick Franklin went 1-for-4 to extend his hitting streak to eight games.