Seattle's ace became the third-youngest pitcher since 1952 to reach 1,000 strikeouts, pitched 7 1/3 strong innings and led the Mariners to a 4-2 win and a split of their day-night doubleheader Wednesday.
Boston won the opener 5-3 behind Josh Beckett, and a sweep, on a night when the New York Yankees and Tampa Bay Rays lost, would have cut its deficit from 6 to 4½ games against those teams who share the AL East lead. Instead, the Red Sox trail by 5½ with 34 games left.
On Friday, they start a three-game road series against Tampa Bay.
"It's very important, obviously," said second-game loser Tim Wakefield. "It's one of the teams we're chasing and it would have been nice to get a win tonight to take a little bit of momentum going down there."
Instead, Boston's winning streak ended at four as Hernandez (10-10) struck out nine, giving him 1,002, and allowed four hits and one walk while the Mariners snapped a four-game losing streak.
"You know every time he takes the mound something special can happen," Seattle interim manager Daren Brown said. "Sometimes we lose [track] of what he's done and he's only 24 years old. He's a valuable guy for this organization and he's going to be a big part of it for years to come."
Boston scored an unearned run in the third and trailed 4-1 when Wakefield (3-10) left after 5 2/3 innings. J.D. Drew hit a solo homer in the sixth, the first earned run off Hernandez in 27 2/3 innings over four starts. The Red Sox threatened in the eighth with runners at second and third and one out.
Then Brandon League replaced Hernandez and pitched 1 2/3 scoreless innings for his fourth save in nine chances.
Hernandez lowered his ERA from 2.51 to 2.47, second in the AL to Clay Buchholz of the Red Sox at 2.26. He recorded his 1,000th strikeout when he fanned David Ortiz in the sixth, at the age of 24 years, 139 days. Only Bert Blyleven (23 years, 121 days) and Dwight Gooden (23 years, 249 days) did it at a younger age.
"I feel happy for that. I feel most happy we won the game," Hernandez said.
Wakefield made his first start since July 20 as a late replacement for Jon Lester, who was pushed back to Friday's game against the Rays. Daisuke Matsuzaka was scratched from that game with soreness in his lower back.
"That's a lot to ask, but [Wakefield] did a very good job," Boston manager Terry Francona said. "Facing one of the better pitchers in the league, we gave ourselves a chance to win."
The night game was a makeup of Tuesday night's rainout. A downpour hit Fenway Park on Wednesday morning but both games were played without delays.
Seattle made it 4-1 in the sixth on Matt Tuiasosopo's RBI double.
The only hit off Hernandez through five innings was Kalish's double in the third. With one out in the sixth, Drew hit his 17th homer and Victor Martinez singled but the next two batters were retired.
In the opener, Boston scored the first four runs in the sixth while Beckett, who was 0-2 with a 10.69 ERA in his previous three starts, gave up just one hit.
But the Mariners drove Beckett (4-3) from the game with three runs in the seventh on a solo homer by Branyan and a two-run shot by Casey Kotchman. After he left with one out in the inning, the Mariners were held hitless by Daniel Bard for 1 2/3 innings and Jonathan Papelbon in a perfect ninth for his 32nd save in 38 opportunities.
If Beckett gets on a roll, Boston's playoff chances would improve, but he doesn't know if that will happen.
"If I can pitch like I did the first six innings, yeah," he said. "If I pitch like I did in the seventh inning, no, probably not."
For five innings, Beckett dueled with David Pauley (2-5), whose only major league wins came in his previous two games. Pauley allowed two hits until getting knocked out of the game in the sixth.
"I started losing the grip of the ball," he said. "For the most part, my fastball was good. The fifth, sixth inning was when the ball was wet."
Marco Scutaro led off the sixth with a single and took second on Martinez's one-out single to left. Ortiz walked, loading the bases. Adrian Beltre followed with a hard single off Pauley's glove as Scutaro scored the first run.
Mike Lowell hit a sacrifice fly and Daniel Nava made it 4-0 with a two-run single. Jamey Wright replaced Pauley and struck out Bill Hall to end the inning. Darnell McDonald singled in Boston's last run in the eighth.
Francona and Beltre were thrown out by plate umpire Dan Bellino after the second inning of the second game. Beltre had argued a third strike call in the bottom of the second and was ejected after taking his position at third. He said he was trash-talking in Spanish with Hernandez, a friend, and didn't direct any comments toward Bellino. ... Branyan has homered in 36 of the 39 ballparks in which he's played after connecting for the first time at Fenway. The three he hasn't homered in are Target Field in Minnesota, which opened this year, Nationals Park in Washington, which opened in 2008, and Veterans Stadium in Philadelphia, where the Phillies played from 1971 to 2003. ... The doubleheader was the first for both teams this year. ... Beckett has at least one strikeout in each of his 243 games, the longest active streak in the majors to start a career.