OAKLAND, Calif. - Five extra days of rest worked wonders for Seattle Mariners right-hander Felix Hernandez.

Mariners manager Lloyd McClendon had Hernandez skip his scheduled start Monday at Houston to "freshen him up" for September, and he opened the month by pitching a gem Saturday night as Seattle recorded an 8-3 win over the Oakland Athletics at the O.co Coliseum.

Hernandez (16-8) gave up three runs on six hits, struck out nine and walked none in the Mariners' fourth straight win. With 16 wins, Hernandez moved into a tie for first in the American League with Astros left-hander Dallas Keuchel.

Hernandez said he didn't know if the extra rest "made a difference" in his performance, but he acknowledged that it "probably" helped.

"I feel good today," said Hernandez, who went 7-7 with a 4.95 ERA in his previous 16 starts. "I had good command, except for the fourth inning. After that everything was fine. Good pace, good mechanics."

The hot-hitting Mariners gave Hernandez more than enough support. First baseman Logan Morrison hit a two-run homer in the third inning, his 16th blast of the season, and left fielder Shawn O'Malley hit his first career homer, a solo shot in the fourth. Right fielder Seth Smith went 3-for-4 with two doubles, walked once and scored twice. Third baseman Kyle Seager had two hits, including an RBI double.

"I think we're doing a great job of swinging at strikes, letting balls go and letting the starting pitcher kind of get himself in a hole and taking advantage of runners in scoring position," said Morrison. "Getting big hits, moving runners, hitting homers and driving the ball."

O'Malley went 2-for-2 with a home run and a double, walked twice and scored two runs in his second game since being called up Tuesday from Triple-A Tacoma. He said he shocked himself when he homered.

"I haven't hit a ball out in (batting practice) all week," O'Malley said. "So the fact that it came in the game couldn't have been better."

Rookie first baseman Mark Canha hit his 12th home run of the season, a solo blast leading off the fourth inning for Oakland, which lost its fourth straight game. Catcher Stephen Vogt had two hits in four at-bats and scored a run, and designated hitter Billy Butler went 2-for-3 with two RBIs.

Hernandez improved to 22-8 overall for his career against Oakland and 11-3 at the Coliseum. He's tied for second with Mike Flanagan for the most victories by an opposing pitcher at the Coliseum, one behind Tommy John.

Athletics right-hander Jesse Chavez (7-14) had his shortest start of the season, giving up five runs on six hits over two innings. He struck out two, walked a season-high five and fell to 0-6 for his career against Seattle. Chavez leads the American League with 14 losses and is tied for the major-league lead.

"It's me leaning back too much and sitting in a chair instead of using my legs and the mound to my advantage," Chavez said. "Things tend to go side-to-side instead of north and south when I lean back. What's going on is inconsistency. One inning it will be good, one inning it will be bad. I have to get back to basics and let my stuff work."

The Mariners built a 3-0 lead in the first inning. Shortstop Ketel Marte led off with a four-pitch walk and moved to third on Seager's single. Second baseman Robinson Cano lined an RBI double off the left-center field fence, and Chavez walked Smith on four pitches to load the bases.

Morrison grounded into a force play, driving in Seager and moving Cano to third. Center fielder Brad Miller brought Cano home with an infield single.

"When he doesn't have his good fastball, it seems like his other pitches all come in at the same speed," A's manager Bob Melvin said of Chavez.

The Mariners increased their lead to 5-0 in the third when Smith lined a leadoff single and Morrison launched Chavez's 1-0 pitch into the right-field seats. O'Malley led off the fourth with a home run to right off A's reliever Arnold Leon, making it 6-0.

The A's scored three runs in the bottom of the fourth. Canha drove a leadoff home run over the right-center field fence, ripping Hernandez's 1-2 fastball. With two outs, Vogt lined a single to left and Lawrie moved him to third with a sharp double down the left-field line. Butler followed by grounding a two-run single to center.

"He relaxed a little bit with two outs in the (fourth) inning, but other than that I thought he threw the ball pretty good," McClendon said of Hernandez.

NOTES: Oakland RF Josh Reddick left the game after the second inning because of an illness. ... Mariners DH Nelson Cruz (strained right quad) was out of the lineup for the second straight game Saturday against Oakland. Cruz said he felt "better," but he didn't take batting practice Friday and could miss Sunday's series-finale. "I'd say right now it's probably 50-50," Mariners manager Lloyd McClendon said. ... Seattle LF Franklin Gutierrez (strained groin) was out of the starting lineup Saturday against Oakland. Gutierrez was injured Friday night, leaving that game after the top of the second inning. "Feels a little better," McClendon said. "It wasn't as bad as we thought it was." ... A's LHP Sean Nolin, who was recalled Friday from Triple-A Nashville, will make his Oakland debut and his second major-league start Sunday against Seattle. "I've been waiting for it all year," said Nolin, who came to Oakland from Toronto in an offseason trade.