BOSTON -- The thunder returned to Boston's offense on Monday night. Electricity came back to Fenway Park, which had been unusually quiet during a frustrating three-game weekend sweep to the White Sox.

A series the Red Sox probably need to sweep to have even a fighting chance to stay in contention was kicked off with a 12-5 victory over the Rays. Boston trails Tampa Bay by 6 1/2 games and the White Sox by a half game in the American League Wild Card standings with 24 games left in the season.

If Sunday's loss seemed as deflating as any the Red Sox have had in 2010, there was no carryover.

"This weekend was tough," said Sox slugger David Ortiz. "We played some good games but just didn't score enough runs in the first two games, and [Sunday] was a crazy day when we scored some runs and they bounced back and scored some. There's not much you can do about that but come back and play the way we did today."

The offense erupted early, as Ryan Kalish's grand slam in the bottom of the fourth gave Boston an 11-2 lead. It was Kalish's second slam and third career homer. The two slams by a rookie tied a club record, last achieved by Bob Zupcic in 1992.

"Oh man, what a good swing," said Red Sox manager Terry Francona. "I mean, [Andy] Sonnanstine at the time looked like he was having trouble commanding. He got a little cutter that came back over the plate and took a very welcome swing. Good for him."

It was fitting that the big hit was delivered by a rookie. Much of buzz before the game centered around the promotion of Lars Anderson, who made his Major League debut, getting the start at first base. While Anderson went 0-for-4, he thoroughly enjoyed watching his friend Kalish produce the game-breaking slam.

"It was great to see," said Anderson. "I'm not surprised at all. That guy is one of the most dynamic players I've seen as far as all the tools just being together. It's pretty fun to watch."

Kalish has been playing almost every day since his arrival on July 31.

"We have a lot of young guys coming with a lot of talent," said Ortiz. "It's good to watch them do good things so you can count on them the following year."

But next year wasn't on Kalish's mind when he stepped up with the bases full against Sonnanstine with two outs in the fourth.

"Obviously I'm just trying to work a good count and stay relaxed up there," Kalish said. "That situation can get tense and he really was throwing a lot of cutters. It was a 3-1 count, I was just looking for something in your zone, and I was trying to hit the ball hard and it was really nice to hit one out."

Tampa Bay's difficulties started long before Kalish's slam.

Ortiz (two-run shot) and Adrian Beltre smacked back-to-back homers in the bottom of the first, swiftly overcoming the 1-0 lead Tampa Bay built in the top of the first.

"They were both fastballs," said Rays starter Jeff Niemann. "Ortiz was 3-2, he fouled a couple off and I was really trying not to walk him. Beltre, I thought that was a pretty good inside fastball that he turned on and got it."

The problems for Niemann intensified further in the second. Kalish led off with a single and with two outs, Tampa Bay's starter walked Daniel Nava and J.D. Drew. Victor Martinez capitalized by ripping a two-run single to right. Sonnanstine came on in relief, but not much changed. Ortiz smashed an RBI double off the Monster.

Riding the wave of support was lefty Jon Lester, who overcame a 29-pitch first inning to improve to 16-8 on the season. Lester threw 94 pitches over his six-inning stint, allowing four hits and two runs while walking three and striking out 10.

"I've always said it makes it easier pitching when guys go out and score runs like they did tonight," Lester said. "That was a big game for us."

With a big lead, Francona sent righty Robert Coello out for his Major League debut to start the seventh. But that didn't go well at all. Coello got just one out while allowing three this, three runs and two walks. Dustin Richardson came in and walked the only batter he faced. But Scott Atchison (1 2/3 shutout innings) and Hideki Okajima (scoreless ninth) restored order.

The Red Sox will try to chip one game closer Tuesday night when Daisuke Matsuzaka faces David Price.

"Confidence is a huge thing," said Kalish. "Like I said, I try to go out there every day and not put too much pressure on yourself. You can't get too high on things, you can't get too low. Tomorrow you have to come back and get another win. We're playing from behind, and tonight hopefully can give us a spark."