Perhaps as a goodwill gesture, manager Don Wakamatsu put Sweeney in the starting lineup for the series finale and Sweeney did something special.
Fans gave him a warm ovation.
"I think he left a lasting impression here," Wakamatsu said. "He is loved here, was a team captain, set a good example, and he's well-respected. For him to hit his 100th home run in this stadium, I think was a big day for him."
One of the biggest, Sweeney admitted.
"There's a chance that this will be the last game I ever play at Kauffman Stadium and if it is, it is something I'll remember for the rest of my life," the 35-year-old said. "I will remember every second of the day. Even though we didn't win the game, getting a chance to start in front of a good crowd, hitting my 100th homer here at Kauffman Stadium and getting the ovation that I did, is something I will never forget."
He said the cap-tipping was his way of saying thanks.
"I poured my heart out here in Kansas City for 13 years and to be welcomed the way I was tonight meant a lot," Sweeney said. "I wanted to acknowledge my appreciation to the fans. It was emotional and I was thankful for that moment."
Sweeney said he would "pray a lot" and talk to his family before deciding whether to continue his career beyond this season -- if a team wants him.
Used sporadically by the Mariners this season, he is batting .239 with four home runs and 18 RBIs in 142 at-bats.
Sweeney's glory days with the Royals started in 1999, when he hit 22 home runs and drove in 102 runs, and ended in 2005 with 21 home runs and 81 RBIs. In between, the five-time All-Star hit 29 home runs twice and peaked with 144 RBIs in '00.
He was to the Royals during that seven-year stretch what Ken Griffey Jr. was to the Mariners in the 1990s -- the main man in the lineup.
It seemed like old times when Sweeney drove a Bruce Chen pitch over the left-field fence with one out in the fourth inning for his 203rd career home run. It was his first at Kauffman Stadium since June 8, 2007 -- a span of 58 at-bats.
The fence-clearing blast put Seattle on the board for the first time and took a small chunk out of the five-run lead the Royals grabbed in the first inning off Mariners left-hander Jason Vargas.
The first inning looked like an extension of pregame batting practice for the Royals.
Vargas walked the first batter he faced, got an out, and then surrendered home run to Billy Butler. That was followed by two singles, a two-run double by Mark Teahen, an out, and run-scoring double by Yuniesky Betancourt.
Vargas settled down after that and took the game through the seventh inning. He delivered more quantity than quality.
Wakamatsu noticed that Vargas tried to overpower the Royals in the first inning with his fastball, left too many of them up in the strike zone and paid the price.
"I talked to him after the first inning," Wakamatsu said, "and I thought he did a heckuva job after that. He and Rob [Johnson] got on the same page and changed styles a little. For him to give us seven innings after throwing 61 pitches in the first two innings was a positive.
"But giving up that amount of runs was not what we were looking for."
Vargas retired the last nine batters he faced, but the Mariners' offense was held in check by previously winless left-hander Bruce Chen and two relievers.
Ichiro Suzuki had another multiple-hit game with two singles, Beltre matched his season high with a 4-for-4 performance and Johnson had two more hits.
However, second baseman Jose Lopez's streak of games with at least one RBI ended at seven. He was 0-for-4, grounding into an inning-ending double play in the fifth and stranding runners on first and third in the seventh.
The loss prevented the Mariners from sweeping the three-game series and dropped them back to nine games behind the Angels in the AL West. Seattle did, however, remain 6 1/2 games behind the Red Sox in the Wild Card.
"It was definitely not the way we wanted to end the road trip," Wakamatsu said, "but I thought we played good baseball here."