Buchholz scattered five hits over eight solid innings in a 6-1 victory over the Chicago White Sox.
"Everything fell right into place," said Buchholz (17-7), who struck out five and walked one. "It's been pretty fun this season and I've got one more start."
A Red Sox loss would have locked up playoff spots for the Tampa Bay Rays and New York Yankees. Instead, Boston took an early lead, pulled away and stayed mathematically alive in the wild-card race while the Rays and Yankees lost.
The magic number remains at one for the Rays and Yankees to reach the postseason.
Buchholz never gave up more than one hit in any inning, and had trouble in only one when he had runners on second and third with no outs in the third.
"Boy he was sure good," Red Sox manager Terry Francona said. "All his pitches he threw for strikes. It was fun to watch."
Mark Buehrle (12-13) gave up 11 hits in six innings, taking his third straight loss even as he hit 200 innings pitched for the 10th straight season.
"Buehrle was struggling today," White Sox manager Ozzie Guillen said. "That's a pretty good hitting lineup and they're going to hurt you."
Martinez extended his hitting streak to 12 games with a single to center in the first inning. Beltre doubled off the wall and both came home on Ortiz' two-out double which skipped past Paul Konerko down the first base line.
Martinez had a sacrifice fly in the third inning RBI that scored Scutaro, who led off the inning with a double down the third base line.
In the fifth, the Red Sox had two runners on and one out for Beltre, who drove home Scutaro with a single to left for a 4-0 lead.
White Sox third baseman Brent Morel broke the shutout in the fifth with a deep sacrifice fly that scored A.J. Pierzynski. Three White Sox tagged Buchholz for deep flies in he seventh, all caught at the warning track.
Beltre doubled home Martinez in the ninth to extend the Red Sox lead to 6-1.
Ortiz's two RBIs gave him 100 for the season and Beltre's two gave him 101.
"It's always nice to get 100 RBIs and to help the team out," Beltre said. "But a good year would have been better if everyone would have been healthy."
The Red Sox have won seven of eight, including a six-game winning streak that was snapped in Sunday's 4-3, 10-inning loss at New York that put them on the brink of elimination. ... The White Sox came in on a four-game winning streak. ... Buchholz missed a chance for his second complete game of the season when he was pulled after eight innings in favor of Scott Atchison, who worked the ninth. His only complete game came on June 4, an 11-0 decision over Baltimore. ... Guillen confirmed Monday that he'll be back as White Sox manager in 2011. ... White Sox CF Alex Rios left the game in the eighth when he was struck in the left knee by his own foul tip. Alejandro De Aza completed the at-bat and grounded to first. "That's the best swing he got in two weeks," Guillen said. "He's got a pretty good bruise." ... Chicago's Carlos Quentin reached base three times with a walk, a hit and a hit by pitch. It was the 20th time he's been hit, second-highest in the AL.