Triston Casas has been on a rehab assignment in Worcester since July 30, and over the past two weeks the Red Sox first baseman has worked to dial in his swing and timing so when he arrives in Boston, he’ll be ready.

When exactly he comes back remains an open question, but with his rehab assignment due to expire next week Casas’ return is now imminent.

“I expect him to be with us whenever it ends,” manager Alex Cora said Sunday.

Specifically, Casas’ rehab assignment expires on Aug. 20, meaning the latest he could be activated is during the club’s upcoming road series in Houston, which runs Aug. 19-21. Casas could potentially return before then too, but Cora said they don’t expect him back for this week’s home series against the Texas Rangers.

“(Head trainer Brandon Henry) talked to him last night and he feels like he still needs more,” Cora said. “We’ll keep getting him at bats. He feels close to 100% — 100% for him is how he bounces back the next day, how he bounces back from batting practice and his four at bats and all that. He’s still going to be down there, most likely next week he’ll still be there, and then we’ll see what happens.”

Entering Sunday Casas was batting .267 with five doubles, four RBI and an .822 OPS through eight games with the WooSox. Casas hasn’t played in the big leagues since April 20, but once he returns he figures to give the Red Sox offense a huge boost.

Sox face tough call with Dom

Casas’ return will also force the Red Sox into a tough decision.

Dominic Smith, who was acquired largely to fill in for Casas, has performed well lately and is batting .264 with an .829 OPS since the start of July. He’s been one of Boston’s best hitters during that stretch, but he and Casas are also both left-handed hitting first baseman with limited positional versatility, meaning it will be hard for the club to carry both on the active roster.

Whether or not the Red Sox can find a way to keep Smith around will be a question to watch as Casas’ return nears.

Hendriks feeling good

Liam Hendriks (Tommy John rehab) came out of Saturday’s bullpen session feeling good and is expected to throw a third bullpen later this week, likely on Tuesday or Wednesday. If all goes well the veteran closer could begin a rehab assignment soon after. … Right-hander Brayan Bello (paternity leave) will be back with the team on Monday as is scheduled to start Boston’s series opener against the Texas Rangers. … Nick Pivetta (arm fatigue) is expected to make his next start on Thursday in Baltimore. Tanner Houck will start Wednesday’s series finale against the Rangers. … Trevor Story (fractured shoulder) will take batting practice on the field Monday for the first time since suffering his injury in April.