Hernandez, the ace who led the AL with a 2.14 ERA last season, gave up one run. He struck out four and walked none.
''Changeup was nice, slider was good, fastball was unbelievable,'' Hernandez said. ''Got a lot of ground balls. It was good.''
Manager Lloyd McClendon thought so, too.
''Very good outing, one that I was anxious to see. It was very important to get him built up, get him up and down five or six times. He got the pitch count up where he needed to be,'' McClendon said.
Hernandez retired the side in order in four of his six innings. A leadoff double by Christian Colon followed by a wild pitch and Jarrod Dyson's sacrifice fly in the third produced the Royals' run against Hernandez.
''It was good. Able to throw all my pitches for strikes and felt healthy and strong,'' Guthrie said. ''Kept it down for the most part.''
Ryan Jackson hit a two-run single with two outs in the eighth off reliever Danny Farquhar, who is in contention for a Seattle bullpen job.
Royals relievers Jason Frasor, Kelvin Herrera and Ryan Madson each pitched a scoreless inning.
Madson hasn't pitched in the majors since 2011 because of complications from previous injuries.
''We're really pleased with what he's done so far. That's been a really good find for us,'' Royals manager Ned Yost said.
The competition remains open for what might be six of seven bullpen spots on the Mariners' opening-day roster, with right-handed closer Fernando Rodney the only sure thing. Two of the spots could be for left-handers with four more for right-handers. Charlie Furbush figures to be one lefty - he threw a scoreless inning Thursday. Veteran Joe Saunders and rookies Tyler Olson and David Rollins are competing to be the second lefty.
Olson continued to make his case Thursday, retiring the only batter he faced. He hasn't allowed an earned run in eight spring appearances (9 2-/3 innings).
Royals: Guthrie is already slotted as the fifth starter in the rotation. He'll get one more spring training outing in Arizona and will throw at some point when the Royals play in Houston before the regular season starts.
''It was his day,'' Yost said. ''He was just sharp. He was executing all his pitches. His changeup was just phenomenal. He was consistently down in the zone ... Hernandez looked really, really good and Guthrie just matched him.''
Mariners: Hernandez is in line for one more start before he takes the ball on opening day. He finished his afternoon with some additional pitches in the bullpen.
''I feel I'm where I want to be,'' Hernandez said. He's looking forward to an opener in Seattle in front of the King's Court, his legion of devoted fans that occupy sections at Safeco Field.
''Going to be fun. It's been a while,'' he said. ''You've got to be pumped. But I'll be calm.''
Royals: OF Alex Rios is day-to-day with a bruised thumb.
Royals: Opening day starter Yordano Ventura has a 10.29 spring ERA, but he allowed only a run on four hits in five innings on March 21. He starts Friday against Seattle.
Mariners: James Paxton continues to work his way back to regular-season form after an injury delayed his start to spring training. He'll start vs. the Royals on Friday.