BOSTON – Daisuke Matsuzaka and Adrian Beltre are doing their best to keep the Boston Red Sox in playoff contention.

Matsuzaka pitched eight strong innings and Beltre hit a grand slam Thursday night to lead Boston to a 6-2 victory against the Cleveland Indians, earning a split of the four-game series.

“Every game from here on is a must win,” Matsuzaka said, “so I think the most important things about today is we got a ‘W.’ “

Going into their game July 4, the Red Sox were a half-game out of first place in the AL East. Now, after a rash of injuries, they trail the first-place New York Yankees by six games for the division lead and Tampa Bay by 5 1/2 in the wild-card race.

Matsuzaka (8-3) allowed Shin-Soo Choo’s 14th homer of the season in the first inning but gave up just four more hits and never faced more than four batters in any inning. He is 5-1 in his last 10 starts and has allowed three earned runs or less in 10 of his last 12 outings.

“Matsuzaka had tremendous control and he was tough,” Indians Manager Manny Acta said. “We aren’t claiming to be a hitting machine type of club, but he had a good arsenal.”

Matsuzaka struck out six, walked two and allowed five hits. After Jayson Nix led off the seventh with a single, Matsuzaka retired the last six batters he faced, finishing by getting Choo on a groundout.

“I knew that if I let anybody on base that would be the night for me, so I needed to get those (last) three outs,” Matsuzaka said.

Beltre is batting a team-high .336 with 20 homers and a club-leading 75 RBI. He connected for his grand slam in the fourth off Josh Tomlin (1-1), who retired Boston’s first 10 batters.

“It was a fastball right in the middle,” Tomlin said. “I lost the first few hitters and got out of rhythm. The fourth inning killed me and I paid when I made a mistake.”

Jonathan Papelbon got his 26th save in 31 opportunities when he struck out Trevor Crowe with the bases loaded for the final out.

Matsuzaka “gave us a lot of pitches to hit and we just didn’t,” Crowe said. “He challenged us but we just didn’t take advantage.”

Marco Scutaro singled with one out in the fourth for Boston. After David Ortiz flied out, Victor Martinez and J.D. Drew walked before Beltre hit a 1-0 pitch for his eighth grand slam and first since Sept. 21, 2006.

It extended his hitting streak to 11 games, during which he’s batting .356.

“He continues to just take ferocious swings without losing sight of what he’s doing,” Red Sox Manager Terry Francona said.

The homer capped Beltre’s big series against Cleveland. He started it by driving in all of Boston’s runs in a 6-5 loss Monday night, and finished 6 for 15 with four runs, three homers and nine RBI.

Drew drove in Boston’s last two runs in the eighth with a single.

Cleveland scored on Luis Valbuena’s ninth-inning single off Hideki Okajima before Papelbon took over.

CLEVELAND CATCHER Carlos Santana will have surgery today on his left knee and miss the rest of the year.

Santana was hurt Monday night in a home-plate collision with Ryan Kalish of Boston.

The Indians said the recovery time is four to six months and Santana is expected to be ready for the 2011 season.