"He made me look ... ," said Davis, trailing off about his two strikeouts on six pitches.
He looked just fine in his third time up against Seattle's ace.
Davis' drive gave Texas a 6-4 lead and sent Kevin Millwood to his first win over Seattle in his last six starts. Michael Young also hit a two-run drive off Hernandez as the Rangers increased their major league-leading home run total to 46.
"That's something [Davis] is capable of," Young said. "He's got big power and he can have a couple of at-bats where the pitcher might win the battle, but you always know whenever he gets to the plate we have a chance to score some runs. He's one of those rare guys that can put runs on the board in a hurry."
Millwood (3-2), who retired the first 12 batters he faced, allowed five runs and eight hits in 7 1/3 innings. He has pitched at least seven innings in each of his six starts this year and earned his first win over the Mariners since July 23, 2007, by outlasting Seattle's young star.
"You put up six runs against that guy, you've got to win the game," Millwood said. "Besides me, I thought our game was solid all the way around."
Frank Francisco got Adrian Beltre for the final out of the eighth and worked the ninth to continue his dominant pitching. Francisco hasn't allowed an earned run since Aug. 18 and is 8-for-8 in save chances this year, but this one was a little shaky.
Franklin Gutierrez singled with two outs and Yuniesky Betancourt walked before Ichiro Suzuki flied out to end the game. It was the fourth straight one-run game for Seattle and came a day after its 15-inning victory over Oakland.
After consecutive brilliant performances, Hernandez (4-1) finally got tagged in the fourth as the Rangers pieced together four straight hits to end his scoreless innings streak at 22. Hank Blalock zipped an RBI double past Endy Chavez in left-center field and Marlon Byrd followed with a run-scoring single.
Young hit a hanging slider out in the fifth and Davis stepped up in the sixth, golfing a breaking ball into the seats in right.
"My first two at-bats, six pitches, two strikeouts. It wasn't very productive," Davis said. "I wasn't sitting on it, but I thought, 'I'm probably going to see a breaking ball here.'"
Seattle manager Don Wakamatsu said Hernandez has been fighting a mild flu, but the right-hander was more concerned with the pitches he left over the plate.
"I feel bad. But no excuse for that," Hernandez said. "I feel like the pitches were there, and they gave me four runs and I [couldn't] handle it."
Seattle finally got to Millwood in the fifth. Millwood left a 3-1 fastball out over the plate to leadoff batter Russell Branyan, who hit his seventh homer. Jose Lopez singled with one out and Kenji Johjima doubled before Gutierrez's tying three-run homer into the Rangers bullpen in left.
Seattle scored in the seventh when Suzuki beat out a double play allowing Gutierrez to scamper home, but Suzuki was stranded at second.
Hernandez went 0-4 against Texas last year and Millwood was 0-3 against Seattle. ... DH Ken Griffey Jr. was expected to be in the lineup, but had a flare-up of a colon condition called diverticulitis that was initially diagnosed in late 2006. Griffey says it usually takes a couple of days to get over. ... Rangers OF Josh Hamilton played catch on Monday, his first baseball activity in a week as he rehabs from a strained left rib cage muscle.