SEATTLE — The Seattle Mariners are set to begin the second half of the season with the first of a three-game series against the San Francisco Giants at 7:10 p.m. PT on Friday at T-Mobile Park in Seattle.

The Mariners will enter the game with a losing record (48-49) and one game behind the Texas Rangers for first place in the American League West.

A large part of Seattle's struggles in the first half of the season was due to injuries suffered by both position players and relievers.

One of those players, three-time All-Star Julio Rodriguez, has been on the seven-day concussion injured list since July 3 after getting hit in the head by a throw from first base while he was trying to take second.

Rodriguez missed the team's final road trip of the first half, which was comprised of three-game series losses against the Miami Marlins and Tampa Bay Rays, respectively.

Rodriguez wasn't in the lineup for the first game of the second half, but he went through a full pregame workout Friday before the game against the Giants. If he is able to get through the workout and not show any symptoms during or after, he could be activated for the second game of the series against San Francisco.

"(Rodriguez) will take some swings in the cages off the traject," Mariners general manager Justin Hollander said in a pregame interview Friday. "If that goes well, we'll see where he is tomorrow in terms of ready for activation (off the IL) or if he needs more time. ... We just need to check every box before he comes out here and plays in a major league game."

Rodriguez is slashing .259/.323/.424 with a .747 OPS in 87 games this season with 15 doubles and 14 home runs with 40 RBIs.

-- Injured right-handed Seattle relievers, Cooper Criswell, Matt Brash and Carlos Vargas, are all set to return in the next month to month-and-a-half. Brash is in a throwing assignment and will return around mid-to-late August. Criswell's ETA is late-August to early-September, per Hollander. Vargas is set to return from mid August and is set to throw a bullpen July 21.

"I would say (between) Brash, Criswell and (Vargas), Vargas is probably the closest," Hollander said.

-- OF/DH Rob Refsnyder, who's on the IL due to knee inflammation, will begin a rehab assignment with the Triple-A Tacoma Rainiers with Saturday. 

-- Utility player Brendan Donovan will be the team's designated hitter for the Rainiers on Friday. He'll have off days worked into his rehab assignment and will play "all over the field," per Hollander. He began his rehab assignment as a DH for the Arizona Complex League Mariners on Wednesday.

Hollander said the rehab assignment "needs to be what it needs to be" due to Donovan being out for two months, but tentatively said a 10-day rehab assignment could be the plan for Donovan.

-- Infielder Leo Rivas, who's been on the injured list for Tacoma since June 17 due to vertigo-like symptoms, is trending upward and was activated off the IL for the Rainiers on Friday.

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