SEATTLE — Guillermo Heredia’s two-out pinch RBI single in the ninth inning Thursday night lifted the Mariners to a 5-4 walk-off victory over the Chicago White Sox.
And saved them from the potential sting of a crushing loss.
The Mariners let a 4-0 lead slip away when reliever Casey Lawrence served up a two-run homer in the seventh inning to Matt Davidson before Dan Altavilla gave up successive two-out homers in the eighth inning.
Taylor Motter started the winning rally with a leadoff single to right against White Sox lefty Dan Jennings.
After Jarrod Dyson fouled off two bunts in attempting to sacrifice, he got one into fair territory — but right back to Jennings, who threw out Motter for a force at second.
Dyson reached second on Chooch Ruiz’s grounder to third, which prompted an intentional walk to Jean Segura, whose three-run homer in the fifth inning boosted the Mariners to a 4-0 lead.
Heredia pinch-hit for Ben Gamel to provide a right-handed bat against Jennings and punched a single to right. Dyson scored easily.
Rookie Sam Gaviglio did his part by pitching five scoreless innings before handing a four-run lead to Lawrence, whom the Mariners acquired May 11 from Toronto in a waiver claim.
The Mariners pulled Gaviglio after 75 pitches because of endurance concerns; he had thrown just two innings over the previous 13 days.
Lawrence worked scoreless sixth but yielded a two-run homer in the seventh to Davidson, which cut the Mariners’ lead to 4-2.
The White Sox pulled even when Todd Frazier and Tim Anderson hit two-out homers in the eighth inning against Altavilla.
That stuck Gaviglio with a no-decision and pulled Chicago starter Dylan Covey off the hook for a loss after allowing four runs in six innings.
Earlier, Dyson gave the Mariners a 1-0 lead by turning on a first-pitch fastball from Covey in the third inning.
Dyson drove it 360 feet into the right-field seats for his second homer of the season — which matched a career high.
Next time up, Dyson had a two-out single to left in the fifth inning. He then stole second and third, which gave him a league-leading 12 steals, before Covey walked Ruiz.
Segura followed with a three-run homer to left for a 4-0 lead. Segura went down and clubbed a 1-0 slider for a 402-foot drive that also extended his hitting streak to 17 games.
Gaviglio had an eight-pitch first inning. He pitched around a two-out double in the second, a two-out walk in the third and a two-out triple in the fourth before stranding two runners in the fifth.