HOUSTON — Before their biggest regular-season series in years, the Houston Astros will welcome back a much-needed bat.

Houston plans to activate All-Star third baseman Isaac Paredes off the injured list prior to Friday’s series-opener against the Seattle Mariners, a league source told The Athletic, ending a 55-game absence during which the Astros’ lineup struggled to score runs with any consistency.

The Astros averaged just 4.1 runs per game after Paredes suffered a significant right hamstring strain on July 19. Houston somehow went 28-27 during the stretch, posting a .309 on-base percentage, .387 slugging percentage and a .695 OPS that ranked 24th in baseball.

In August, Paredes chose to receive a platelet-rich plasma injection to treat the hamstring strain in lieu of season-ending surgery that, according to general manager Dana Brown, would’ve sidelined Paredes for six months. Paredes hoped to return in time for a potential playoff series and, for all intents and purposes, is doing so. The Astros are tied atop the AL West with Mariners, who they will host for three games this weekend at Daikin Park.

Paredes has spent the last two weeks taking live batting practice at-bats at the Astros’ spring training complex in West Palm Beach, Fla. Reports from both Brown and manager Joe Espada said Paredes was progressing well. As of Wednesday afternoon, Espada said Paredes had received 14 live at-bats at the complex.

“He is doing very, very well,” Espada said on Wednesday. “I think every day he comes in feeling better. His recovery time is better. Getting ready for his daily routine is getting easier for him. I’m really happy where he’s at.”

Still, it’s unclear how effective — or healthy — Paredes will be during Houston’s final nine regular-season games. Both Paredes and Espada have acknowledged that he could be limited to a designated hitter role, which the Astros will need filled in the wake of Yordan Alvarez’s severe left ankle sprain.

“It was a very difficult injury,” Espada said of Paredes before Wednesday’s game. “Right now, he is checking all the boxes and he feels good. Are we going to be expecting him to go 100 percent around the bases? No. I’m going to ask him not to. I’m going to ask him to make sure that he can give us the effort he can give us to just stay on the field.”

Alvarez’s injury on Monday further magnified the need for Paredes’ bat in the Astros’ lineup. Prior to his hamstring strain, Paredes slashed .259/.359/.470 and had a team-high 19 home runs, most of which were pulled into the Crawford Boxes at Daikin Park — emphasizing why Houston had long coveted Paredes’ offensive profile.

Paredes’ patience and plate discipline have also been missed by an Astros lineup that sees the second-fewest pitches per plate appearance in baseball and chases outside the strike zone more than any American League team. Paredes saw an MLB-high 4.43 pitches per plate appearance last season and, before his injury, averaged 4.40 in this one.

(Photo: Alika Jenner / Getty Images)