Harrison has befuddled Seattle for several years now. The big southpaw is 10-1 with a 2.14 ERA in 17 career games (13 starts) against the Mariners, including 4-0 with a 1.10 ERA in four meetings this season.
He's won nine straight decisions against Seattle, a mark exceeded only by the 14 straight wins by Dave Stewart from 1986-90 and 12 by Pedro Martinez from 1998-2004.
"Harrison was tough," said Smoak, who homered for the second straight night. "He's been tough against us every time we've faced him. I think a lot of teams would say that. But it's one of those things where we'd get somebody on, but we weren't able to get them in. There just wasn't much going on against him."
Blake Beavan pitched well for the Mariners, giving up just two runs on seven hits over seven innings, but couldn't quite match Harrison as he fell to 9-10 with a 4.88 ERA.
Adrian Beltre broke a scoreless tie with a solo home run in the fourth off Beavan, depositing a 1-0 fastball into the left-field seats for his 33rd home run and 93rd RBI of the season. Beltre has eight home runs in the last 15 games and 14th in his last 24 for Texas, which opened up a three-game lead over Oakland in the AL West.
The Rangers got to Beavan again with an RBI double by Mitch Moreland in the fifth in what stood up as the winning run.
"I don't know what the radar said, but I felt good today with my location and where I was missing," Beavan said. "I just tried to focus on finishing all my pitches. Just the pitch to Beltre, the one I didn't finish, that's how it happens. He's one of the hottest hitters right now and you're not going to get away with much with him right now."
Beavan started on 11 days' rest after being pushed back in the rotation to allow rookie Erasmo Ramirez to take a turn in Toronto at the start of the road trip. The 23-year-old is now 1-2 in Rangers Ballpark this season, having lost a 1-0 decision in his first start of the year and winning a 21-8 blowout in May.
The Texas native joked about getting angry watching the Cowboys losing to the Seahawks during the rain delay, but he definitely has thrown well now in three games in a tough pitcher's park.
"I guess I need to start doing better with my thinking process because when I play in parks where the ball [flies], I concentrate a little bit more," he said.
With Harrison shutting down Seattle's offense, Beavan was back to the low end of the run-support scale in this one. The Mariners managed just four singles off Harrison in the first seven innings and three of those were negated by double-play groundouts.
The 240-pound Harrison improved to 17-9 with a 3.26 ERA, becoming the first Texas lefty to win 17 games since Kenny Rogers in 1995, as he just missed his second shutout of Seattle this season.
"Everything we needed from him he gave to us," said Rangers manager Ron Washington. "That should put to rest him being fatigued."
Until Harrison walked Franklin Gutierrez and gave up a two-out single to Jesus Montero in the ninth, no Mariner advanced past first base outside of Smoak on his 16th home run of the season. Smoak went 2-for-3 on the day.
Seattle manager Eric Wedge said Smoak should be able to build off his success over the weekend. Though he's hitting just .199 on the year, he went 5-for-7 with two home runs and four RBIs in the past two games. Smoak homered from the left side on Saturday and from the right on Sunday.
"He needs to take that confidence from here and keep going, because what he did here was real," Wedge said. "You can see what he does for us as a ballclub when he's on his game offensively. He's a guy that can really give us a big boost."
Seattle (70-77) finished up its road trip at 3-3 and is now 7-9 on the season against Texas, with one final three-game set with the Rangers scheduled for this coming weekend at Safeco Field.