DENVER -- Jesus Montero and Justin Smoak hit back-to-back home runs, Blake Beavan tied a season-high with seven strikeouts and the Seattle Mariners held on to beat the Colorado Rockies 6-4 on Sunday to complete a three-game sweep.
Mike Carp also homered and Dustin Ackley had two hits for the Mariners.
Carlos Gonzalez homered among his three hits and Dexter Fowler also homered for Colorado, which has lost four straight overall and 8 of 10 at home in May.
The Mariners were 8-4 on the road after sweeping a series in Detroit last month before losing 12 of their last 13 away from home. Coors Field proved to be a cure for their struggles, but not without a tense ninth inning.
Leading 6-2, closer Brandon League came on and gave up a one-out, pinch-hit homer to Fowler, his fifth. Eric Young and pinch-hitter Jason Giambi followed with singles, and Gonzalez knocked in a run with a single to center.
Troy Tulowitzki hit a potential double-play ball to third, but Smoak bobbled the relay at first to keep the inning alive. League struck out Todd Helton to end the game.
Beavan (2-4) followed strong outings by Seattle's starters in the first two games with five-plus innings of two-run ball. He gave two runs and seven hits while walking one to get his first win since April 15.
Beavan's only mistakes were a two-out solo homer to Gonzalez and a two-out RBI single by Jordan Pacheco. He left after giving up a leadoff double to Michael Cuddyer in the sixth, but righty Shawn Kelley got Wilin Rosario to line out and struck out Pacheco and pinch-hitter Tyler Colvin.
Colorado's Jeremy Guthrie (2-2) allowed three homers in a game for the fifth time in his career.
The Mariners jumped out to the early lead for the third straight game. Ackley led off the game with a double, moved to third on fly out and, after a walk to Kyle Seager, the two successfully completed a double steal to score the first run. Seager scored on Smoak's two-out single to make it 2-0.
Gonzalez cut the lead in half with his eighth home run in the bottom of the first before Seattle's big bats woke up.
With two outs in the third, Montero hit a two-run homer to left, his sixth, and Smoak followed with fifth homer into the front row of the right-field bleachers to make it 5-1.
Pacheco's RBI single in the fourth made it 5-2 but Carp's fourth homer off the second deck in right in sixth put Seattle ahead 6-2.
Guthrie left after giving up six earned runs, striking out seven and walking two in six innings. He didn't get much help from his offense, which went 2 for 16 with runners in scoring position.
NOTES: The Rockies recalled RHP Adam Ottavino from Triple-A and optioned LHP Rex Brothers. ... Mariners C Miguel Olivo will join Triple-A Tacoma in Iowa on Monday to begin a rehab assignment. Olivo has been on the DL since May 5 with a strained right groin. ... Mariners RHP Felix Hernandez will face Texas RHP Yu Darvish in the opener of a three-game series in Seattle on Monday. ... Colorado will send lefty Jamie Moyer against Marlins lefty Mark Buehrle in Miami on Monday.