SEATTLE — Right-handed reliever David Phelps continues to progress in his throwing program and could be ready to rejoin the Seattle Mariners’ bullpen in time for the key upcoming weekend series at Tampa Bay.

Phelps, 30, was diagnosed as having an impingement in his elbow, which forced his exit after facing only one batter Aug. 6 at Kansas City. An examination two days later projected a recovery timetable of two-to-three weeks.

It now appears Phelps will be on the shorter end of that projection. He is expected to test his recovery over the next day or two by throwing from a mound for the first time since the injury.

“If that goes well,” manager Scott Servais said, “a sim game (would follow) and then we’d activate him. Fingers crossed, maybe something in a 10-12 day range (from the injury). Probably 14 (days) which, originally, was what was said.”

That suggests the Mariners don’t believe Phelps will require a minor-league rehab assignment before returning to active duty.

The Mariners open a three-game series Monday against Baltimore and, after an open date, begin a four-city trip next weekend with three games at Tampa Bay.

Phelps was 1-1 with a 2.57 ERA in seven appearances after the Mariners acquired him from Miami in a July 20 trade for four minor-league players. He is 3-5 overall with a 3.33 ERA in 55 games.

Felix building strength

Right-hander Felix Hernandez is still at the strength-building stage in his recovery from a second bout with bursitis in his shoulder. He was placed on they disabled list Aug. 5 and an examination projected a recovery timetable of three-to-four weeks.

“He’s on anti-inflams,” Servais said. “He hasn’t started throwing or anything like that. He’s trying to ramp up the arm exercises to build strength.”

Hernandez, 31, missed two months earlier this season while batting the same injury. He is 5-4 with a 4.28 ERA this season in 13 starts.

Tuesday’s starter TBA

Servais said the Mariners haven’t yet determined a starter to replace injured James Paxton for Tuesday’s game against Baltimore.

Paxton is expected to miss at least three weeks after suffering a strained left pectoral muscle Aug. 10 in a start against the Los Angeles Angels.