Instead, Jackson squared up the first pitch he saw, a 93-mph fastball with movement, shooting the ball just inside the right-field line to score Logan Morrison for a 6-5, walk-off win.
"I was just looking to get a good pitch in the zone and not trying to do too much," Jackson said. "You hear that all the time, but especially in that situation -- going into extra innings everybody's having a good at-bat and you really just want to go up there and put a good swing on it."
As Jackson sprinted up the first-base line, he said he wasn't sure if he had the game-winning hit. Even after umpire Jeff Nelson signaled for a fair ball and the remainder of what had been nearly 25,000 fans at Safeco Field erupted in cheers, he was worried it had just been a close call because of a delayed reaction from his teammates.
"Man, you know what, I really didn't know," Jackson said. "I still didn't know if it was fair, even when he called it fair, I was like, 'Oh, I don't know." Because nobody really reacted.
The mood was the same in the first-base dugout, where the Mariners weren't sure if they had their sixth walk-off win of the season.
"We were screaming to keep it fair," said manager Lloyd McClendon. "He put a good swing on a tough pitch and got the big hit for us."
Jackson's batting average has stayed right around .250 for much of the season, but his walk-off knock broke a recent dry spell. Jackson had one hit in his last 12 at-bats and has shared center-field duties with newcomer Ketel Marte of late.
Tuesday's game, in which Jackson notched two opposite-field hits and made a return to the leadoff spot, might give him some momentum. At the very least, it gave him his first walk-off hit since April 5, 2012.
"I guess it hit the chalk, and the rest is history," Jackson said.