Harrison allowed five hits and no runs, and got five homers from his teammates as the Rangers routed the Kansas City Royals 10-1 on Saturday night. Mitch Moreland, Mike Napoli and Endy Chavez hit consecutive homers in the second to match a club record.
The last big league team to go back-to-back-to-back was Boston at Texas on Aug. 13, 2010.
Harrison was thankful for the big early advantage.
"It's definitely a lot easier to pitch with a lead like that," he said. "We had six runs by the third inning, so your mentality then is to just go out and pound the zone. You don't have to be as fine, because they're probably going to take a couple of pitches to work the count and try to get some walks, but I was able to keep them swinging the bats throughout the game."
Harrison (5-4) struck out one and walked one in steamy 98-degree conditions to help the Rangers win for the fourth time in six games. He has pitched at least six innings in eight of his 10 starts and has thrown 16 1/3 straight shutout innings in his last three starts.
Harrison could have gone deeper, but a blister on his right index finger shortened his outing. Team president Nolan Ryan recommended that Harrison take a seat for the rest of the night.
"It just popped up, I think, after the fifth inning," Harrison said. "It was a blood blister and I went back out for the sixth and it started getting bigger and bigger. I wanted to go back out for the seventh, but I guess they consulted with Nolan and he said it was probably time to shut it down and get it taken care of so I dont miss a start."
Yoshinori Tateyama, a 35-year-old rookie, worked the final three innings for his first big league save.
O'Sullivan was knocked around for 10 runs and 15 hits -- both career highs -- in 5 2/3 innings as his ERA swelled from 5.60 to 6.75.
Already battling right biceps tendinitis that limited the effectiveness of his fastball, the 23-year-old right-hander knew he'd have to go deep into the game because the Royals' bullpen had thrown 11 1/3 innings of shutout relief in Friday night's 12-7 win over Texas in 14 innings.
"It's not fun," O'Sullivan said. "But I had to keep taking the ball and go as hard as I could for as long as I could. I'd have finished it if (manager Ned Yost) kept running me out there."
O'Sullivan said he's experienced the tendinitis before and has been able to pitch through it.
Billy Butler had two hits for the Royals, who've dropped 11 of 14.
If O'Sullivan thought he was getting a break facing Texas' bottom three batters to open the second, he was mistaken.
Moreland led off with his sixth homer into the visitors' bullpen in left center, Napoli followed with his seventh, and Chavez hit his first to make it 5-0. The three blasts sailed a total of 1,182 feet.
Napoli had been in a 4-for-25 slump that dropped his average from .313 to .183.
"We go up to the plate trying to hit the ball hard somewhere and let the result happen," Napoli said of the second-inning long-ball barrage. "We were hitting the ball all over the place. Things were going good for us."
The Rangers knocked out O'Sullivan with a three-run sixth on Josh Hamilton's RBI double and Cruz's two-run homer for a 10-0 lead.
Former Ranger Matt Treanor ended Texas' shutout bid in the seventh with an RBI groundout.
Texas manager Ron Washington said he's spoken to RHP Neftali Feliz about mixing in more offspeed pitches with his fastballs. The closer had his third blown save in 13 chances in Friday night's loss to the Royals and has been relying heavily on the fastball. "I know this: It will get straightened out," Washington said. ... Hamilton returned to LF after four games at DH. ... Rangers RHP Scott Feldman was thought to be on track for a minor league rehab assignment, but that's on hold due to soreness in his surgically repaired right knee from Friday's bullpen session. He'll continue exercises to strengthen the knee. ... O'Sullivan has given up 27 runs in his last four starts. ... A scoring change for a game on May 14 against the Angels took an RBI single away from Young and credited Angels SS Erick Aybar with an error. Young also lost an RBI in the MLB review process. ... Cruz had three hits, snapping an 0-for-15 skid with a third-inning single.