So when Venable got a fastball, he turned on it and hit the ball right past first baseman Kendrys Morales, sending the Padres to a 3-2 victory in front of 19,882 fans.
It was the third career walk-off hit for Venable, who was met by a mob of teammates as he rounded first base.
"With infield in, I'm not trying to manipulate [the ball] too much," Venable said after receiving a Powerade shower during his postgame on-field interview. "I'm just trying to hit a ball hard."
The Padres loaded the bases in the eighth, ninth and 10th before finally breaking through off Medina (1-1). The win improves the Padres to 24-28 as they have won two in a row over the Mariners (22-31) after dropping the first meeting in this four-game Interleague series.
Padres starter Eric Stults was at his best, lasting eight innings while surrendering one run on three hits and striking out a career-high 12. He is the first Padres pitcher to record 12 K's in a game since Jake Peavy on May 6, 2009, and just the third pitcher in club history with at least 12 K's and no walks.
"He's pitched some very good games for us ... but I don't know how you throw any better than that," Padres manager Bud Black said. "That's impressive."
Stults said he had command of all four of his pitches and took advantage of the Mariners' aggressiveness, throwing fastballs with two strikes when he thought the Mariners were sitting on off-speed pitches.
"That kid was funky, like something we haven't seen this year the way he was throwing the ball," said Mariners manager Eric Wedge. "The big slow breaking ball, then he had great arm action on the changeup that would just kind of die against right-handed hitters. And then he kept you honest with a fastball at about 90, which looked about 100 compared to the other two pitches. He did a good job."
The Padres left the bases loaded in the eighth where a run would've put Stults in line for the victory, but failed to score off Mariners reliever Carter Capps.
Then Jason Bay led off the ninth inning with a solo home run off Huston Street to give the Mariners a 2-1 lead. Street, who kicked the dirt on the mound after Bay's shot, has allowed seven home runs on the season, an uncharacteristically high number for the Padres' normally reliable closer. But he settled down and retired the next three hitters in order.
Once again the Padres battled back, loading the bases in the ninth before tying the game on Kyle Blanks' sacrifice fly against Mariners closer Tom Wilhelmsen, who blew only his second save of the season.
The Padres received a scoreless 10th from Luke Gregerson (3-2), who picked up the victory.
Mariners starter Joe Saunders was also very good, holding the Padres to just one run -- a first-inning homer by Chase Headley -- on four hits in seven innings and also didn't allow a walk.
But after Headley's home run, Saunders settled in and retired 12 of the next 13 batters.
However, the Padres had their chances late in the game and left 10 runners on base. "Our guys, they play to the last out," Black said.