Boston Red Sox manager Alex Cora says his side are not suddenly a bad offensive team and brushed off talk of a slump after going down 3-2 in the American League Championship Series (ALCS) to the Houston Astros.

The Astros triumphed 9-1 on Wednesday to move within one game of the World Series, backing up from Tuesday's 9-2 win.

The Red Sox only managed three hits for the game on Wednesday, with Astros pitcher Framber Valdez starring across eight innings.

The defeats mean the Red Sox have allowed nine or more runs and been held to five or fewer hits in back-to-back games for the first time ever at Fenway Park.

"I don’t see it as a slump, it's two games," Cora said during his post-game news conference.

"We've been really good defensively the whole month. Tonight that kid [Valdez] was amazing. We'll keep working and talking. We'll be ready as a group."

Game 6 will take place in Houston on Friday, offering the Red Sox a chance to recoup and reconsider their plans after the Astros flipped the ALCS.

"We know we can hit," Cora added. "Two bad games doesn’t mean that all of a sudden we're not a good offensive team.

"It's a matter of a re-group, make some adjustments and attack from the first pitch on.

"We've got to win two games to go to the World Series, that's the bottom line."

Cora insisted he would not make any personnel changes to his Red Sox line-up for Game 6, backing in Hunter Renfroe who has had a lean ALCS, with only one hit.

Renfroe has not homered all postseason, after blasting 31 with 135 hits and 96 RBIs during the regular season, hitting at .259.

"He's a guy throughout the season who has done an amazing job," Cora said. "He's played great defense for us and he's been good offensively. We'll keep rolling them out there."

Cora was full of praise for Valdez, who had five strikeouts, describing his sinker as "unreal" and claiming he was the difference.

"Their guy was amazing," he said. "He was throwing harder than usual, the ball was moving, we didn’t hit the ball hard at all.

"Credit to him. His sinker was unreal tonight. You tip your hat to him and you move forward."

Boston Red Sox manager Alex Cora says his side's "humble approach" led to their historic multiple grand slam Game 2 performance as they won 9-5 over the Houston Astros.

The Red Sox levelled the American League Championship Series (ALCS) after J.D. Martinez and Rafael Devers delivered grand slams in the first two innings.

Boston became the first team in postseason history with multiple grand slams in a game, while there are only five other occasions when a side has hit grand slams in the opening two innings across any majors game, mostly recently in 1984.

Enrique Hernandez also homered in the fourth inning, continuing his excellent run of recent form, setting records for most XBH (nine), hits (15) and total bases (34) across a five-game postseason span.

In seven games, Hernandez has also already tied the Red Sox record for most home runs (five) in a single postseason.

"I think when we have this humble approach that we're not trying to do too much, then big things happen," Cora said at the post-game news conference.

"And J.D., that was great to see [him] going the other way. Raffy, not trying to do too much and hitting the grand slam. It's a very good approach right now. We're not getting greedy.

"Like I said a few days ago, it's not about hitting 30 home runs or driving [in] 100 runs. It's about winning four games against the Astros. So now we got one, and now we go to Fenway."

Cora also hailed starting pitcher Nathan Eovaldi, who improved his record to 8-1 in postseason games for the Red Sox when he plays, including 5-0 when he starts.

Eovaldi lasted five-and-one-third innings, giving up three runs on five hits, one walk and three strikeouts.

"He's been a horse for us, he's been amazing and he went out there and did an amazing job," Cora said.

Cora, whose Red Sox are 5-2 this postseason, was delighted his side would take the series to Boston after splitting the opening two games in Houston.

Alex Cora praised the calm of Nathan Eovaldi as he put his previous performance against the New York Yankees to bed to lead the Boston Red Sox to victory in their Wild Card clash.

Eovaldi was given the start on the mound at Fenway Park on Tuesday as the most famous rivals in baseball squared off for a place in the American League Division Series.

That meant Eovaldi dispelling memories of 11 days prior when he gave up seven runs on seven hits in an 8-3 loss to the Yankees in a series in which New York claimed a critical sweep to propel them to the Wild Card game.

Eovaldi lasted fewer than three innings in that game, which saw him fail to strike out a single hitter and issue two walks.

He was at his best when it mattered most in the postseason opener, however, pitching a shutout through five innings and striking out eight Yankees before being removed by manager Cora in the sixth following a home run from Anthony Rizzo.

His display laid the platform for the bullpen to finish the job, as the Red Sox clinched a 6-2 victory.

"He's so calm. When he shows up to the ballpark, he's the same guy when he pitches and when he doesn't. He was waiting for this one," Cora said of Eovaldi in his post-game media conference. 

"They [the Yankees] did an amazing job on Friday [September 24]. They took some pitches away, they hunted pitches in certain spots, and they did damage. Like I said, we learned a lot from that.

"He's just a great person. He's not only a great pitcher but he's a great person. He cares about everybody; the way he goes about it in the training room, in the weight room, when he doesn't pitch, he's a plus. We had the right guy on the mound today."

The Red Sox now face the challenge of taking on another AL East rival, the Tampa Bay Rays, in the ALDS.

Tampa Bay finished the regular season 100-62, the third-best record in baseball and the best in the American League.

"Now we go to the next one, and we've just got to be ready to face a great baseball team," added Cora. 

"Probably coming into the season, everybody talked about them being the best team in the big leagues, and we have a huge challenge. But we're ready for it."