As the visiting Boston Red Sox prepare for the middle game of a pivotal three-game series against the Kansas City Royals, they expect to soon receive a bullpen boost with the return of right-handers Chris Martin and Justin Slaten.

On the injured list since July 4, Martin may return during the series with the Royals.

“He’s on his way here,” Boston manager Alex Cora said on Monday. “He’s staying at home one more night. We’ll know more (Tuesday) night. If he’s ready, he’ll be activated Wednesday.”

Slaten, dealing with right elbow inflammation like Martin, has been sidelined since July 8.

“(He was) playing catch (Monday), up to 120 (feet),” Cora said, “so, that’s a good sign. When you get up to there, the bullpen is right around the corner.”

The Red Sox recently received surprising news about Trevor Story, who has missed all but eight games due to left shoulder dislocation and was thought to be lost for the year.

Instead, the shortstop has made significant progress and could return this season.

“I never thought we were going to get to this point,” Cora said. “I’m excited. Obviously, not a hundred percent that it’s going to happen, but the fact that he is doing everything possible to make it happen is great.”

Story is travelling with the club and swinging a bat.

“He’s hitting underhand tosses, front tosses this past weekend,” Cora said. “That’s close to BP. He’s moving well. His swing looks great.”

After winning the series opener 9-5 on Monday, Boston will send right-hander Brayan Bello (10-5, 5.13 ERA) to the mound on Tuesday as they look for their third straight series victory.

In two career starts against the Royals, Bello is 1-0 with a 2.77 ERA. He collected a win on July 14 vs. Kansas City despite surrendering homers to Salvador Perez and Adam Frazier. He threw 6 1/3 innings, allowing three runs on seven hits.

In three starts since, Bello has been consistent, throwing at least five innings while allowing three or fewer runs each time.

The Royals will counter with right-hander Seth Lugo (13-5, 2.57 ERA). He has made four career appearances — one start — against the Red Sox, going 0-2 with a 7.56 ERA. The lone start was a loss on July 13, when he allowed five runs on 10 hits, including a home run by Rafael Devers, in five innings.

Lugo beat the Detroit Tigers in his latest start, allowing a run on four hits in eight innings on Thursday.

“A lot of soft contact, a lot of pitch efficiency,” Royals manager Matt Quatraro said. “It looked like he had everything working. He got soft contact on changeups, some swing-and-miss on the breaking ball, had the two-seamer going. All in all, he was in command the whole night.”

While Bobby Witt Jr. has earned most of the Royals’ offensive headlines, teammate Vinnie Pasquantino has also contributed as Kansas City has homered in 11 straight games, tied for the fourth-longest streak in club history.

In the Monday loss, Pasquantino extended his hitting streak to nine games with his 16th homer. He has five long balls in his past six games.

“Vinnie’s a run producer,” Quatraro said. “He’s had some good games for us, especially lately.”

In 35 games since June 24, Pasquantino is hitting .329 with nine homers and 34 RBIs. His 51 home-game RBIs lead the majors.