ARLINGTON, Texas — If you are speculating about the players who will join the Mariners for the September roster expansion, manager Scott Servais confirmed that four players on the injured list will be activated Sunday — the first official day.

Right-handed pitchers Brandon Brennan (shoulder strain) and Dan Altavilla (forearm strain) and outfielder Braden Bishop (lacerated spleen) were in the clubhouse before Friday’s game. They worked out pregame and will do so Saturday but can’t be in the dugout during games. All three are expected to be activated from the injured list. Brennan and Altavilla each tossed scoreless innings Thursday night in Fresno for Class AAA Tacoma.

Right-hander Austin Adams (lat strain), who is going to pitch once more for Class AA Arkansas, is also expected to be activated Sunday.

“We’ll need the pitching for sure,” Servais said.

Servais said the Mariners won’t call up the full 40-man roster.

“That’s too many,” he said. “You can’t play them all. It leads to too many guys on vacation and sitting around. That’s not what we want. We’ve got a lot to do over the next five weeks and some opportunities for some guys. Maybe we’ll get up to 33 or 34.”

The Mariners are expected to call up two touted prospects — outfielder Kyle Lewis and right-handed pitcher Justin Dunn — from Class AA Arkansas once its season ends. Both players will need to be added to the 40-man roster. Right-hander reliever Art Warren is another candidate. First baseman Evan White is not expected to be called up. The Travelers made the Texas League postseason and open a series versus the Tulsa Drillers on Wednesday in Little Rock.

Infielder Shed Long (broken finger) was activated from the 7-day injured list for Class AAA Tacoma on Friday. He’s expected to play for the Rainiers in their last four games in Las Vegas and join Arkansas for the playoffs. He could also be a September call-up once the Texas League postseason is finished.

With the Mariners off Wednesday following a two-game series in Chicago, ROOT Sports will televise Class AA Arkansas’ opening game of the Texas League playoffs against the Tulsa Drillers. Brad Adam will do the play by play with Mariners general manager Jerry Dipoto serving as analyst for the live broadcast.