The right-hander has not allowed a run over his last four appearances since Oct. 22 thanks to a devastating split-finger fastball.
"I was mostly just getting ahead of hitters with the fastball and they were chasing my split in the dirt," said Buente, who threw 20 of his 30 pitches for strikes and allowed two hits and a walk. "We've been playing really well lately."
Steve Singleton hit a game-tying two-run homer and fellow Twins prospect Chris Parmelee knocked home the go-ahead run with a sacrifice fly an inning later to give Buente a chance to keep the lead intact.
"It's nice when you know you'll be pitching, especially knowing we got the lead," said Buente. "It makes it a lot easier to pitch."
Singleton, who has eight RBIs in his last nine games, knotted the game in the fifth with his second homer of the Fall League season, a one-out shot to right off Cesar Valdez (Diamondbacks). Parmelee drove in Starlin Castro with a two-out fly to center field in the sixth inning for his 17th RBI of the fall.
Marlins lefty Jay Voss got the win with a pair of scoreless frames before Buente bridged the gap to closer Chris Province, a Red Sox right-hander who worked the ninth for his second save.
Buente, who pitched well at Triple-A New Orleans in the regular season, said he's hoping a strong performance in Arizona will translate into a role with Florida's bullpen in 2010.
"I had somewhat of a rough start, but I'm just getting my feet wet here," said Buente, a 26-year-old from Evansville, Ind. "I've made a few adjustments, started throwing four-seamers instead of two-seamers. I have a lot better command that way."
Buente did just fine without his four-seam fastball in 2009, finishing a combined 5-2 with a 3.14 ERA in 51 appearances between Double-A Jacksonville and New Orleans. He struck out 56 in 61 innings at Triple-A with a save and five wins.
A new, or rather, rediscovered pitch -- the four-seamer -- may accelerate Buente's path to the Marlins in February camp.
"I know my organization will let me know when they think I'm ready they'll give me an opportunity, hopefully next year. I'm hoping to get an invite to Spring Training," said Buente, Florida's 14th-round pick in the 2006 Draft. "I hope to make the team. They'll tell you when, and hopefully I throw well out here."
Buente replaced Voss to begin the seventh and struck out Thomas Neal (Giants) and Brandon Allen (Diamondbacks). He walked Giants catcher Buster Posey but induced a inning-ending grounder from the Rockies' Wilin Rosario.
The 6-foot-2 Buente escaped trouble in the seventh, striking out Jose Tabata (Pirates), Brandon Crawford (Giants) and Domonic Brown (Phillies) after allowing consecutive hits to begin the inning.
"I'm getting ahead of hitters -- this is definitely a hitter's league," he said. "They'll jump on the fastball. I'm kind of developing the four-seamer, I haven't thrown a four-seamer since 2007. I've made some adjustments and liked it a lot, so I'm sticking with the four-seamer here."
Buente's two-seam fastball has some sinking action and rides inside on right-handed batters, although he said his improved four-seam grip has yielded better accuracy. He hopes to pair both variations with his splitter next summer in Miami.
"I need to work on fastball command, that's one of the biggest things I need," he said. "My split is my out pitch, so today I didn't use it right away -- mainly with two strikes."
Buente posted strong numbers with Class A Advanced Jupiter in 2008, finishing 5-1 with a 3.00 ERA and 63 strikeouts in 60 innings. He knows the Marlins are watching his progress with Mesa (10-12) this fall.
"I know for some guys, and for me, this is a time to develop and mainly to show your organization that you're ready," he said. "I'm trying to do both, get better and do well. I don't put pressure on myself though -- a bad outing, I'll learn from and get better. You just want to continue to get better and you'll get to your goal. I'm not too nervous about it."
Rockies shortstop Hector Gomez homered in the third for Scottsdale (9-13).
Phillies right-hander Edgar Garcia allowed one run on one hit in the sixth to suffer the loss after Scorpions starter Chaz Roe (Rockies) struck out four over three scoreless frames.