SEATTLE - With a full count in the bottom of the 11th inning, Seattle's Chris Iannetta was looking for a pitch to hit.

He got it and gave the surging Mariners a series sweep.

Iannetta jumped on a 3-2 pitch from Steve Geltz for a leadoff homer to give the Mariners a 6-5 victory over the Tampa Bay Rays on Wednesday and a sweep of the three-game series.

Iannetta's third homer of the season salvaged the victory for Seattle, which was unable to hold an early 4-0 lead.

"If he threw a slider up in the zone, I was hoping I could make contact with that, or a fastball down ... luckily get to two strikes and get something out over the plate," he said. "Ideally, you don't want to go the deepest part or to centre field here, but I'll take it."

It was the second game-deciding home run allowed by Geltz in the series, who gave up a three-run homer on his first pitch in the sixth inning of Seattle's 5-2 victory on Monday.

"Just a little unfortunate," Rays manager Kevin Cash said. "Geltz's M.O. is he's going to throw a lot of fastballs, and if a guy catches up to it, especially those ones at the waist, they can sometimes go a long ways."

The Mariners, 16-6 over their past 22 games and 7-1-1 in their past nine series, escaped a one-out, bases-loaded jam in the 10th.

Steven Souza Jr. reached on a one-out walk off Vidal Nuno, advanced on a passed ball and moved to third on Logan Morrison's bloop single to left.

Steve Johnson (1-0) relieved and walked Steve Pearce to load the bases. Kevin Kiermaier fouled out to third and Hank Conger bounced into a force at second.

"I kind of put myself in a tough spot, first time with the bases loaded," said Johnson, who recorded his first major league victory since May 29, 2013. "I didn't have my best command, but I was able to get a curveball in there for a strike and kind of keep them off balance and make a couple pitches and get out of it."

The Rays tied it 5-5 on Kiermaier's one-out solo homer in the ninth.

With Mariners closer Steve Cishek unavailable after a four-out save Tuesday night, Nick Vincent came on in the ninth to protect a 5-4 lead. After Pearce struck out, Kiermaier lined a 2-0 pitch over the wall in right for his fourth home run.

Nelson Cruz's seventh-inning sacrifice fly snapped a 4-4 tie after the Rays had erased a 4-0 deficit on Corey Dickerson's first career grand slam in the sixth.

Robinson Cano opened the Mariners seventh with a double to right-centre and advanced on a wild pitch. Cruz then lofted a fly to left and Cano scored easily ahead of the throw.

Seattle starter Taijuan Walker cruised through five innings, allowing just two hits, before walks set up Dickerson's game-tying slam.

After Brandon Guyer doubled with one out in the sixth, Brad Miller and Evan Longoria drew consecutive walks off Walker, who had walked just three in 32 innings in his first six starts.

Dickerson then lined the first pitch over the centre-field wall for his eighth homer.

"It got away from him, but it shows you what can happen if you don't command the strike zone," Mariners manager Scott Servais said of Walker. "His stuff was outstanding, he was really cruising, but the walks and then he makes the mistakes on the grand slam and before you know it he's out of the game. You can't let your guard down obviously in this league. He just lost it for a little bit."

The Mariners capitalized on starter Chris Archer's wildness for a three-run first. Norichika Aoki singled and Ketel Marte walked. After Cano struck out, Archer walked Cruz and Kyle Seager to force in a run. Seth Smith then followed with a two-run single up the middle.

Cruz opened the third inning with his sixth homer to make it 4-0.

SWEEPSTAKES: The Mariners swept the Rays at home for the first time since Aug. 7-9, 2006.

CANO STAYS HOT: Robinson Cano extended his hitting streak to 11 games with his seventh-inning double. Over that span, he is hitting .449 (22 for 49) with four homers, nine RBIs, four doubles and 10 runs scored.

TRAINING ROOM:

Rays: 2B Logan Forsythe, who missed Tuesday's game with a bruised left shoulder after being hit by a pitch on Monday, was not in the starting lineup on Wednesday, but was improving. "He's still sore, but actually much better today," manager Kevin Cash said before Wednesday's game. "I'm hopeful for Friday. I'm actually hopeful that it heats up out in the sun and he can be ready late in the ballgame if we need him."

Mariners: Reliever Joaquin Benoit, on the 15-day DL since April 22 with right shoulder inflammation, was scheduled to throw Wednesday, manager Scott Servais said. "Benoit is going to throw a bullpen here today and if that goes OK, we could do a sim (simulated) game this weekend," Servais said. ... Reliever Charlie Furbush, on the DL all season with biceps tendinitis, also had a bullpen workout on Wednesday.

UP NEXT:

Rays: After a day off, Tampa Bay returns home for a three-game series against Oakland, before heading back out on an eight-game road trip. Right-hander Jake Odorizzi (0-1, 3.10 ERA) starts Friday for the Rays against Rich Hill (4-3, 2.39 ERA). Odorizzi has five straight no-decisions, tying a club record.

Mariners: Right-hander Nathan Karns (3-1, 3.38) starts Friday for Seattle to open a three-game home series against the Angels. Karns has pitched at least six innings in each of his past three starts, allowing four earned runs in 19 1/3 innings with 20 strikeouts.