Of the 10 teams Guillen has played for in his career, he felt Seattle supported him as well as any of them.
"They really understood when I opened my mouth there, trying to make the team go in the right direction and go hard," Guillen said. "The GM, the manager, everybody really respected me a lot and I really appreciated that. I have a great relationship with a lot of those guys there -- trainers, players, everybody."
Guillen played for the Mariners last season and hit .290 with 99 RBIs. Seattle competed for a playoff spot for nearly the entire year, winning 88 games and finishing second in the division.
This is Guillen's second meeting this year against the Mariners. The Royals played at Seattle for two games in mid-April, and Guillen went 3-for-8.
Injuries have riddled this season's team but there's no question that the Mariners are missing Guillen's bat. He was ranked third in the American League in RBIs as of Friday.
Seattle could have had him, too. The Mariners bought out the remaining year of Guillen's contract last November.
Guillen wasn't in the starting lineup on Friday night, a late scratch because of a sore neck.
"You know how I am," Guillen said. "I'll probably be in there later on in the game. I hate to be on the bench, especially against my old team."
Mark Dent is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.