And Díaz, a 25-year-old who pitched in Double-A last season, survived a nerve-wracking 10th — he walked two and threw a wild pitch that nearly let the tying run score — before handcuffing Ramírez for strike three and his first career save.
“His stuff is unbelievable,” Reds catcher Tyler Stephenson said as his teammates could be heard celebrating with Díaz in the showers. “He got better with Ramírez, when the moment was bigger for him. He did a great job.”
Díaz has not given up a run in 15 of his 16 appearances.
“He’s not fazed,” Reds manager David Bell said. “Obviously, he had a lot of adrenaline tonight, but he channeled that really well and he went after some really good hitters in a tough spot. Great stuff, but the thing that was really impressive is that he walked a couple of guys and then one of the best hitters in the game, got behind and then just made incredible pitches.”
Tyler Naquin homered for the Reds (10-26), who became the last team in the majors to reach double-digit wins — after blowing a 4-2 lead in the ninth and hitting into double plays in four straight innings.
“This game is an example of you just have to keep playing,” Bell said.
Miller’s towering two-run homer into the left-field bleachers off Warren tied it 4-4.
The Guardians had managed just four singles over the first eight innings against rookie Connor Overton and reliever Tony Santillan before Miller followed a leadoff walk to Ramírez with his fourth homer.
Miller’s heroics snatched a win from Overton.
The right-hander allowed just three singles over 7 2/3 innings in Cincinnati’s second straight stellar start. Overton allowed back-to-back hits in the third, retired 15 straight and then gave up a leadoff infield single in the eighth.
Overton got two outs but walked pinch-hitter Franmil Reyes and was pulled by Bell after a career-high 98 pitches.
“I want to go nine (innings) every time,” Overton said. “Obviously, I’m happy but there’s a lot I could have done better.”
His performance came two days after Cincinnati rookie starter Hunter Greene and Warren combined to work eight no-hit innings in a 1-0 loss at Pittsburgh.
The Reds were just the sixth team in the modern era to lose despite not allowing a hit.
The Guardians played their fourth straight game without manager Terry Francona, who tested positive for COVID-19 last week in Chicago and also missed the three-game weekend series in Minnesota.
Acting manager and pitching coach Carl Willis said the 63-year-old Francona is feeling better and nearing a return.
Cleveland first baseman Josh Naylor also remains out.
Naquin, who spent five seasons with Cleveland, gave the Reds a 1-0 lead with his third homer — a shot into the right-field seats off Zach Plesac.
Reds RHP Tyler Mahle (2-4, 5.89 ERA) won for the first time since opening day last week in Pittsburgh. He faces Guardians RHP Cal Quantrill (1-2, 3.93) in the series finale.