WASHINGTON — After hitting three home runs and driving in eight runs in two games following a day off, Anthony Rendon has a message for Washington Nationals manager Dusty Baker:

Keep 'em coming.

A refreshed Rendon continued doing damage Wednesday night, belting a three-run first-inning homer, his eighth of the season, in the Nationals' 5-1 victory over the Seattle Mariners.

"It may not seem like it wears on you as a player," said Rendon, who was out of the lineup for Washington in Atlanta on Sunday. "But that extra two hours of sleep that you don't get really catches up to you. So when you get a day off, you've got to take advantage of it."

Rendon's first-inning blast followed a two-homer, five-RBI night in Washington's 10-1 series-opening victory Tuesday.

He becomes the fourth Washington player to surpass 30 RBIs with 31.

"It seems like I give Anthony a day off from time to time, and he responds," Baker said.

Tanner Roark (4-2) allowed a run while completing seven innings for the first time in seven starts. He allowed eight hits and two walks while striking out eight to the Nationals win a third straight.

"It was good to get runs on the board early, Roark said. "So I relaxed a little bit out there and (made) my pitches."

Mariners rookie Sam Gaviglio (0-1) allowed all five runs — one earned — over six innings as the Mariners lost their fifth straight.

"I got away from my game plan there in the first and it showed," Gaviglio said.

Seattle's Robinson Cano went 3 for 4, including an RBI single and a double that centre fielder Michael Taylor's glove prevented from being a home run.

The Mariners finished 1 for 7 with runners in scoring position.

"It's definitely been frustrating," said Kyle Seager, who scored Seattle's run. "The last little bit's been very frustrating. We don't like to lose. We certainly don't like to lose in the fashion we've been losing."

Rendon had gone 12 games without an RBI before the series, in which he has twice helped Washington to early leads.

In the first inning Wednesday, Trea Turner reached on shortstop Jean Segura's throwing error and scored on Ryan Zimmerman's sacrifice fly.

Daniel Murphy doubled and Rendon's two-out shot cleared the fence in left-centre by a few feet.

Cano's near home run was pulled back from a similar spot in front of the visitors bullpen in the top of the third. Taylor couldn't secure the ball while crashing into the wall, but Roark stranded Cano at second.

"Mikey was the player of the game defensively," Roark said of Taylor, who made a diving catch of Seager's liner in the fifth. "He was all over the field."

TRAINERS ROOM

Mariners: OF Mitch Haniger (oblique strain) joined the team in Washington on Wednesday. "We'll work him out here over the next three or four days and then see how that's progressing to get him out on a rehab (assignment)," manager Scott Servais said.

Nationals: Placed OF Chris Heisey on the 10-day DL with a ruptured right biceps he sustained in batting practice and recalled OF Brian Goodwin. Heisey said he did not believe the injury would be season ending.

THE TIME IS A-CHANGIN'

The teams' season finale was moved up to 12:05 p.m. from 4:05 p.m. because of the threat of inclement weather. The teams have no mutual off days on Seattle's other East Coast trips this season.

HELLO, GOODBYE

Seattle RHP Emilio Pagan was recalled from Triple-A Tacoma on Monday and pitched four scoreless innings of relief Tuesday. Then he was optioned back to Tacoma on Wednesday as Seattle recalled RHP Rob Whalen.

APLIN OF THEIR EYE

Seattle acquired OF Andrew Aplin from Houston for a player to be named on Wednesday and assigned him to Triple-A Tacoma. The Mariners designated RHP Chris Heston for assignment to make room for Aplin on their 40-man roster.

UP NEXT

Mariners: Ariel Miranda (2-3, 4.28) faces the Nationals for the first time. It is the 28-year-old Cuban defector's 20th big league start.

Nationals: Gio Gonzalez (3-1, 2.86) has historically had the better of Mariners slugger Nelson Cruz, allowing him only a single in 13 at-bats and striking him out five times.