"Everybody's feeding off each other," Hamilton said. "Up and down the lineup, one through nine, there are no easy outs. We're focusing on one good at-bat at a time, and it snowballs from there."
Holland (14-5) allowed one run and six hits with six strikeouts and three walks. He has won eight of his last nine decisions, a stretch that began on July 7.
The eight-run fourth simplified Holland's job and continued strong support from his teammates. Texas averages 7.50 runs each time Holland starts, but he said he couldn't afford to relax despite the eight-run lead.
"The big thing is you can't think like that," Holland said. "You've got to go back out and pitch. You've got to stay focused ... [but] that inning was pretty exciting, awesome to watch."
Ian Kinsler also homered for the AL West-leading Rangers, who have won three straight and maintained a three-game lead over second-place Los Angeles, which beat Oakland 4-1 on Wednesday.
The Rangers are 10-1 against the Indians over the last two seasons and have outscored Cleveland 19-5 in the last two meetings.
"That's what a team that was in the World Series last year looks like, a team that will probably win their division," Indians manager Manny Acta said. "We have some catching up to do."
Lonnie Chisenhall homered for the Indians, who have lost seven of nine overall.
Huff allowed eight runs - although only three were earned due to a fielding error in the fourth by Chisenhall at third base on Kinsler's two-out grounder -- and seven hits in four innings.
Cleveland's Shelley Duncan made two leaping catches at the wall in left field in the first inning to rob Elvis Andrus and Hamilton of extra-base hits. Then in the second inning, he made a similar catch in the same area to deny Michael Young extra bases.
"Weird, to say the least," Acta said of three standout catches in a short span by a player not known for his defense. "For three balls to go in the same spot in the first four outs, you're never done seeing new things in baseball. He made good plays on those balls."
But in the fourth, Duncan was unable to flag down Young's double into the left field corner that scored Hamilton, who was on first with a leadoff walk. Young has 196 hits as he pursues his sixth career 200-hit season.
One out later, Napoli hit a two-run homer, a 420-foot drive that landed on the grass hitting background in center field. Andrus' infield single knocked in the fourth run of the inning.
Hamilton followed with his grand slam on a high 1-2 fastball from Huff to complete the eight-run outburst.
"He threw me a heater up, I swung and missed," Hamilton said. "I figured he'd throw it again and he did. I got just enough of the bat on it to get it out."
Huff said the pitch to Hamilton "was supposed to be a fastball down and away and I left it over the middle belt high. He doesn't miss very many like that. You don't keep the ball down, you suffer."
- Texas 3B Adrian Beltre's double in the second extended his career-best hitting streak to 18 games.
- The Rangers will start RHP Alexi Ogando (12-8) in Thursday night's series finale against Cleveland's Fausto Carmona (6-14). There had been speculation that Ogando's turn might be skipped or he might be sent to the bullpen after losing his last three decisions, but manager Ron Washington said the All-Star will stay in the rotation.
- Rangers OF Nelson Cruz took extra swings in early batting practice as he continues to recover from a left hamstring strain. Cruz was activated on Tuesday, and he appeared as a pinch-hitter in the eighth, striking out. Cruz still won't be able to play the outfield for a few more days, although he could be used as a DH.
- Indians OF Shin-Soo Choo is expected to be activated and start on Thursday night. Choo has been on the 15-day DL since Sept. 1 with a left oblique strain.
- Texas OF Craig Gentry is 18 for 18 in stolen base attempts this season after swiping second and third in the third.
- Indians RHP Carlos Carrasco had reconstructive surgery to repair a ligament in his right elbow. Recovery time is estimated at 12 to 18 months.