"I am definitely going to win that game," Smith said.
Smith reached with two outs when Tanner Scott (1-1) dropped a short toss while covering first base for an error. Smith stole second, and Lopes followed with a grounder to Ruiz.
Ruiz took a bit too long to fire to first base, and Lopes beat the throw.
Smith, meanwhile, whisked around third and slid home safely ahead of the relay with an unearned run.
"An opportunity like that, I have no plans on stopping," Smith said. "You're out there that long, you might as well come out on top."
Orioles manager Brandon Hyde didn't fault Ruiz, noting that the flaw in the inning came earlier.
"It was kind of a tough play for Rio because it was a chopper that he either has to come get or play back, and if he plays back he really has to get rid of it," Hyde said. "It was bang-bang at first base, safe, and Mallex continued. Tough play, but the runner shouldn't have been on first base in the first place."
After Crawford hit a three-run homer with two outs in the eighth inning off struggling Mychal Givens to put the Mariners up 6-4, the Orioles pulled even in the bottom half when Austin Hays went deep against Sam Tuivailala following a leadoff walk.
Givens has allowed seven runs over 3 2/3 innings in his last four appearances.
Baltimore starter Asher Wojciechowski had trouble with rookies Long and Kyle Lewis, who had two hits apiece against the right-hander and helped prompt his exit during a two-run fifth inning that enabled the Mariners to pull into a 3-3 tie.
The Orioles regained the lead in the bottom half with an RBI single by Hanser Alberto, but they failed to add to the advantage after loading the bases with no outs.
Making his sixth major league start, Seattle lefty Justus Sheffield gave up four runs and six hits. He remains in search of his first big league win.
Seattle reliever Austin Adams twisted his left knee trying to make a play at first base in the seventh inning and had to be helped off the field. Manager Scott Servais said the knee appeared hyperextended, and Adams will probably get an MRI on Sunday.
QUITE A CROWD
A blanket giveaway for the final Saturday night home game drew a crowd of 22,556, the largest at Camden Yards since a July 16 matchup with the neighboring Washington Nationals brought in 23,362 fans.
Smith scored the winning run but went 0 for 6, ending his streak of reaching base against the Orioles at 19 games. He had a hit in 17 of those games.
Not that it mattered.
"We knew he was going to get on base sometime tonight," Servais said. "That's how he typically wins games. He finds a way to get on base, busted himself to get down the line and then comes around on an infield hit."
Mariners: OF Domingo Santana returned to the lineup as the DH for his first start since Aug. 18. He came off the injured list Tuesday after missing 24 games with right elbow inflammation.
Orioles: The season isn't necessarily over for Mason Williams, who hasn't played since banging into the outfield wall on Tuesday. "He's day to day and he's sore," Hyde said. Hyde believes Williams could be ready to return next week, but added, "I don't know for sure."
Mariners: LHP Marco Gonzales (16-11, 4.14 ERA) makes his 33rd start of the season Sunday in the series finale. In his last start, he blanked Pittsburgh over seven innings.
Orioles: Rookie LHP John Means (10-11, 3.55) helps the Orioles wrap up the home portion of their schedule. He's 7-5 with a 2.86 ERA at Camden Yards.
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