SEATTLE, Wa. -

 When Seattle's Justin Smoak hit a three-run home run in the fifth inning Tuesday night, the Kansas City Royals' chances for a win and perhaps a postseason appearance were in big trouble.

Smoak hit an 0-2 fastball from Bruce Chen (8-4) for his career-matching 19th home run and the Mariners went on to a 4-0 victory, creating a bleak playoff picture for the Royals.

Time is running out - just five games remaining - much distance needs to be covered and two teams need to be hurdled.

 The Royals' three competitors for the two AL wild-card spots - Tampa Bay, Texas and Cleveland - all won Tuesday.

The Royals, down four games in the loss column to Cleveland, need to win every game and hope that both the Indians and the Rangers completely collapse. 

"We just go till they say we can't win it," Kansas City manager Ned Yost said. "We go as hard as we can. Keep playing our best guys and staying after it."

Mariners rookie left-hander James Paxton (3-0), making just his fourth major league start, worked a career-high seven innings, allowing four hits, walking none and striking out a career-high 10.     

"He looked real good. Big, tall kid, straight over the top, straight downhill action on all his pitches," Yost said. "Good fastball, I mean, over-powering fastball at times, got it up to 97, lot of life on it. But downhill pitches are tough to hit, especially fastballs. Good breaking stuff, good changeup, good curveball."