Clayton Kershaw aces key test as Dodgers top the Giants, 4-2

SAN FRANCISCO — Adrian Gonzalez said last month that he thought Clayton Kershaw deserved to be the National League’s most valuable player. Now Gonzalez is certain of it.

“If someone even tries to mention someone else, they’re an idiot,” Gonzalez said.

The latest evidence for Gonzalez’s case was displayed Sunday, when Kershaw pitched eight innings in the Dodgers’ most important game of the season, a 4-2 victory over the second-place San Francisco Giants at AT&T Park.

The Dodgers, who won the last two games of the three-game series, now lead the Giants by three games in the NL West. Both teams have only 13 games remaining in the regular season.

Kershaw was sidelined for the entire month of April with a strained back muscle but is the only 19-game winner in baseball. He limited the Giants to two runs, which somehow raised his earned-run average, from 1.67 to 1.70. He has pitched eight or more innings in each of his last seven starts, the longest such streak by a Dodgers pitcher since Orel Hershiser pitched nine or more innings in nine consecutive starts to close out the 1988 season.

“He’s the best pitcher in the league,” Matt Kemp said.

From the vantage point of Kershaw’s teammates, what made the performance Sunday worthy of admiration was that it looked particularly strenuous.

The fastball that resulted in a groundout by Angel Pagan to end the seventh inning was Kershaw’s 104th of the game.

Kershaw said his elevated pitch count was a result of the Giants’ relentlessness at the plate.

“They made me compete today,” he said. “It was a lot of long at-bats, just fouling pitches off. They got plenty of hits, guys on base, made me make some big pitches. Pitch count got up there, a lot, pretty quick.”

With the Dodgers protecting a 4-2 lead, Manager Don Mattingly sent Kershaw back to the mound for the eighth inning. Mattingly figured he would replace Kershaw with Brian Wilson after Kershaw faced the leadoff batter that inning, the left-handed-hitting Joe Panik.

“It wasn’t a day where he was just cruising through innings,” Mattingly said. “It was a battle. The way he said it, I felt he was out of gas.”

Kershaw forced Panik to ground out on a first-pitch slider, prompting Mattingly to visit him on the mound. Kershaw persuaded Mattingly not to remove him.

“At that point, who am I to stop him?” Mattingly said.

Up came Buster Posey, the former NL MVP who singled in the Giants’ first run in the third inning and lined out to center field in the sixth.

Kershaw struck him out on three pitches, all of them sliders.

Hunter Pence flied out to the warning track in center field for the third out of the inning.

Kenley Jansen pitched a perfect ninth inning for the Dodgers to close out the win.

Kershaw improved his record at AT&T Park to 8-2 in 11 career starts. His ERA in the stadium is down to 0.83, the lowest for any pitcher who has thrown 75 or more innings there.

But if Kershaw did the majority of the heavy lifting Sunday, it was Kemp who produced what was probably the single most important moment.

Kemp’s two-run home run to center field off opposing starter Yusmeiro Petit in the sixth inning extended the Dodgers’ lead to 4-1, placing the game out of the Giants’ grasp.

The home run was the 20th of the season for Kemp, who hit only six last year in an injury-shortened season.

Of Kemp’s 20 homers, 12 were hit in the last 42 games.

“I feel like if I keep playing, the power will come back and everything else will come back,” Kemp said. “It’s been a pretty good second half. Hopefully, it gets better.”

Kershaw was encouraged by Kemp’s return to form.

“It’s good see him get that power back,” Kershaw said. “It’s not easy to go dead-center here in San Fran. For him to go as far back as he did, it showed he’s getting pretty close to healthy, which is awesome.”

dylan.hernandez@latimes.com

Twitter: @dylanohernandez