"It feels pretty good," Hernandez said. "I was hoping to get us started the right way, and with a win it works out pretty good. It's pretty special."
King Felix surrendered one walk while pitching 7 2-3 scoreless innings. He didn't allow a hit until John Jaso doubled to left-center with one out in the fourth, only a couple of hours after the pitcher gifted his former backstop with a Rolex watch for catching his perfect game in August against the Rays.
Hernandez (1-0) outdueled Brett Anderson while making his sixth career opening day start and fifth in a row, retiring the first 10 batters of the game in order.
Franklin Gutierrez hit a two-run single in the fifth to break a scoreless tie, and it held up for Hernandez.
He gave way to Charlie Furbush after allowing Seth Smith's two-out double in the eighth and a walk to Eric Sogard. Furbush walked Coco Crisp and Seattle manager Eric Wedge then went to Stephen Pryor, who got out of it on pinch-hitter Derek Norris' groundout. Tom Wilhemsen closed out the three-hitter.
There wouldn't be any walkoff magic in Game 1. Oakland led the majors with 14 such wins in 2012.
The Mariners snapped a seven-game losing streak to the A's, who had their second-longest unbeaten run in the rivalry over the past 20 years behind a 15-game winning stretch from April 7-Aug. 16, 2006.
They are well accustomed to King Felix, who started the clubs' season opener in Tokyo last spring, then Seattle's home opener against the A's and again in Oakland's home opener.
"It is a bit redundant that we see him as often as we do, such as last year - how many times, three?" A's manager Bob Melvin said. "He pitched great. He was pretty unpredictable tonight."
Anderson struck out the side in order in the first on 13 pitches, getting Gutierrez on three pitches. Then Hernandez topped that in his first time off the mound with a seven-pitch, 1-2-3 inning.
Seattle hardly looked road weary after leaving the Arizona desert and spring training for an exhibition Saturday in Salt Lake City before a flight to the Bay Area and a workout Sunday at the Coliseum. Hernandez delivered a signature performance as Seattle kicked off a seven-game road trip to start the season - four games in Oakland followed by three against the White Sox before opening at Safeco Field on Monday against the Houston Astros.
Hernandez will try for career win No. 100 on Saturday in Chicago. The 2010 AL Cy Young Award winner, who turns 27 on April 8, certainly showed on Day 1 he is plenty stretched out by tossing 109 pitches.
"Shhhhh, don't say it, not yet," he said. "It's going to be special, it's going to be good to finally get to 100. I'm going to try to do it in my second start."
Jaso, traded by the Mariners to their division rival during the offseason, popped out on the second pitch he saw in the first before his fourth-inning double. Then in the sixth, he struck out swinging to end a 10-pitch at-bat and 22-pitch inning for Hernandez.
About 90 minutes before first pitch, Hernandez had a Rolex watch delivered from a clubhouse employee to Jaso, quite the thank-you gift for his part in the ace right-hander's perfecto.
"He broke up the no-hitter," Hernandez said. "I was going to say, 'Dude, what time is it?'"
The A's had their yellow towel-waving sellout crowd of 36,067 back in force just like last fall during the club's remarkable run to the playoffs. Oakland lost in Game 5 of the AL division series to Detroit.
"It was opening day. It's going to be loud, a lot of people," Hernandez said. "I was just on my game, trying to make good pitches. ... They boo me, I said, 'OK, yeah, I'm doing my job.' I know the people in Seattle were watching the game. It was like 50,000 people out there, it was crazy. I said, 'C'mon, I've got to do something good.'"
Anderson (0-1) allowed two runs and four hits in seven solid innings, struck out six and walked four while throwing 108 pitches in his first career start on opening day. The left-hander successfully returned last August following a 14-month recovery from Tommy John reconstructive elbow surgery.
Anderson struck out Michael Morse to start the second then walked Justin Smoak on five pitches. After Kyle Seager singled off Anderson's leg, Jesus Montero grounded into a double play on which second baseman Sogard made a terrific diving stop and backhanded flip to shortstop Jed Lowrie in time for him to throw to first.
The Bay Area awoke to gray clouds and a steady, hard rain, only for the skies to clear and turn blue.
More than four hours before first pitch, ballpark workers with hand-held driers walked through the stands to clean up the seats while Seattle players ran around in right field throwing a football in shorts and T-shirts.
The Mariners, coming off a spring featuring a franchise-best 22 wins, began a season without Ichiro Suzuki for the first time in 13 years. He won the AL Rookie of the Year and MVP awards in 2001.
Notes: Hernandez has a 1.33 ERA with 41 Ks in his opening-day outings - 35 of those strikeouts in five opening starts vs. Oakland. He has allowed six earned runs in those appearances. ... His six starts on opening day matched Randy Johnson for most in club history. ... Anderson is 7-4 with a 1.83 ERA in 14 career starts against the Mariners. ... Oakland invited 15 season ticketholders onto the field for pregame introductions. ... The A's won the 2012 season series 12-7. If the recent pattern provides any indication, over the past seven seasons Oakland has won the even years - 2006, `08, `10 and `12 - and the Mariners the odd years of 2007, `09 and `11.