Harang could be pitching for his spot in the rotation Monday in the start of a four-game series with the Padres, beginning with two contests at Safeco Field.
Losers of eight straight heading into Sunday's matchup with AL West-leading Texas, the Mariners (21-29) won 4-3 in 13 innings with Jason Bay delivering the game-winning single. He was robbed of a game-winning homer in the 11th by David Murphy after Raul Ibanez' solo shot tied the game to lead off that frame.
"It feels great. Not just for me but for everybody," Bay said after helping Seattle end its longest slide since a 17-game stretch July 6-26, 2011. "That was a big sigh of relief for a lot of people."
The Mariners will conclude their five-game homestand with two against the Padres (22-27) before this series shifts to San Diego for games on Wednesday and Thursday.
The Padres, who have dropped four of five following Sunday's 6-5 loss at Arizona, won five of six in this matchup a year ago, including their first sweep in Seattle from June 12-14.
Harang (1-5, 8.58 ERA), 1-2 with a 6.43 ERA in three home starts, is trying to rebound from a pair of road losses. The right-hander, pitching for the first time in two weeks due to lower back stiffness, was charged with seven runs and a season-high nine hits in 3 2-3 innings of Tuesday's 12-0 loss to the Los Angeles Angels.
"About the only good thing that came out of tonight was the fact that the back wasn't an issue,'' he said.
Another rough outing from Harang, who'll make his 300th start, could force manager Eric Wedge's hand in making a switch with his rotation.
"You can't keep putting this kind of heat on the bullpen," Wedge told the Mariners' official website.
Harang, who finished 14-7 with a 3.64 ERA for San Diego in 2011, went 2-1 with a 3.09 ERA in six starts against the Padres last season while with the Los Angeles Dodgers.
San Diego is expected to push back Edinson Volquez and remove Clayton Richard (0-4, 8.54) from the disabled list to start Monday. The left-hander was placed on the DL with an intestinal virus May 5, a day after permitting seven runs - five earned - in 3 2-3 innings of an 8-1 loss to Arizona.
Richard, a loser of three consecutive starts, has since been working on improving his arm slot at Triple-A Tucson, where he went 0-1 with a 2.25 ERA in 12 innings.
Richard has won his last five interleague starts after yielding three earned runs over 6 2-3 innings in a 9-5 home win over Seattle on June 22.
He could get his first look at Kendrys Morales, who went 6 for 14 with a homer, two doubles and a team-best five RBIs in the three-game set against Texas. Morales or Michael Morse could be at first base Monday if Justin Smoak sits out a second game with a strained oblique.
Left fielder Carlos Quentin should be the Padres' DH in at least one of the next two games. He's 6 for 11 with a homer, three doubles, two RBIs in the last three contests. Quentin's one hit in six at-bats off Harang left the park.
San Diego has won six of eight in Seattle.