If the Mariners are to mount a postseason push, they must do it for the remainder of August, and perhaps into September, without longtime ace right-hander Felix Hernandez.

An examination Monday by Dr. Edward Khalfayan confirmed that Hernandez is again battling bursitis in his shoulder — the same injury that forced him to miss roughly two months earlier in the season.

General manager Jerry Dipoto said Hernandez is expected to miss three to four weeks.

Dipoto also announced right-handed reliever David Phelps is expected to miss two to three weeks after being diagnosed Monday by Khalfayan as having an impingement in his elbow.

Phelps left the first game of Sunday’s doubleheader at Kansas City after facing just one batter because of discomfort in his elbow.

The Mariners placed Phelps on the 10-day disabled list Tuesday, which cleared space for first baseman Yonder Alonso on the 25-man roster. The Mariners acquired Alonso from Oakland on Sunday in a trade for outfielder Boog Powell.

Hernandez was placed on the disabled list Aug. 5 retroactive to Aug. 1 after experiencing discomfort in his biceps in a July 31 start at Texas. He was previously sidelined from April 26 until June 23.

Without Hernandez, the Mariners’ rotation consists of James Paxton, Marco Gonzales, Erasmo Ramirez, Ariel Miranda and Yovani Gallardo. The club acquired Gonzales and Ramirez in July trades.

Hernandez, 31, is 5-4 with a 4.28 ERA this season in 13 starts.

The Mariners obtained Phelps, 30, in a July 20 trade from Miami for four minor-league players. He was 1-1 with a 2.57 ERA in seven appearances since joining the club.