CLEVELAND -- Before he could notch his first save in the Major Leagues, Reds rookie Alexis Díaz backed himself into a tight jam and had to battle his way out against one of the toughest hitters in baseball.

Díaz used a sweeping 86.8 mph slider to strike out José Ramírez for the final out of a wild 5-4 win over the Guardians in 10 innings at Progressive Field.

“It means so much to me to get my first career save," Díaz said via translator Jorge Merlos. "It means so much that I am able to do this at the beginning of my career too."

Getting to that moment proved to be a journey.

Reds starter Connor Overton delivered 7 2/3 strong innings and was in position for the win before reliever Art Warren blew the save opportunity in the bottom of the ninth inning, when Owen Miller hit a game-tying two run home run. In the top of the 10th, Guardians reliever Nick Sandlin walked three straight batters and forced home the go-ahead run with his walk to Mike Moustakas.

Reds manager David Bell put the game into the hands of Díaz for the bottom of the 10th.

With the automatic runner on second base, Díaz struck out first batter Oscar Mercado with an 95.8 mph fastball and second batter Luke Maile with an 87.6 mph slider.

With Miles Straw batting, Díaz unfurled a wild pitch that got past catcher Tyler Stephenson and rolled along the wall under the screen. As Stephenson gave chase, Richie Palacios took third base and was heading home when the ball rolled into the Reds' first base dugout.

"I almost jumped out and tried to field it. It’s a helpless feeling," Bell said.

Since Stephenson never touched the ball, Palacios was ordered back to third base under the rules. It saved the Reds from giving up the tying run.

"The rule helped us in that situation," Stephenson said. "[The ball] hit off something and shot into our dugout. You've got to get lucky sometimes. It worked out."

Díaz walked Straw before Stephenson and pitching coach Derek Johnson made a mound visit.

“They told me to just relax," Díaz said. "You have all the stuff in the world to get the last batter out. So relax, go after the next hitter and get him out.”

But first, Díaz walked Steven Kwan to load the bases for Ramírez. Stephenson didn't make another mound visit but he looked at the 25-year-old and motioned for him to breathe.

"I know the fans are getting into it, the noise, you’ve got to take a second and take a deep breath," Stephenson said. "Focus on making your pitches. He did."

Following a first-pitch ball, Díaz got a fastball over to the All-Star Ramírez for a called strike and came inside with another fastball for strike two. Then came the final pitch, the slider that had Ramírez flailing for the final out.

Entering the night, Ramírez had struck out 12 times in 145 plate appearances this season. Over his career, he has struck out in one out of every 8.3 plate appearances.

"Obviously he had a lot of adrenaline tonight, but he handled that really well," Bell said of Díaz. "To start with runners on second base, he hasn’t experienced that at the Major League level. It was great stuff to get a couple outs. The thing that was really impressive was how he walked a couple guys and then, against one of the best hitters in the game, he got behind and made incredible pitches."

Díaz spent last season at Double-A Chattanooga and made the Reds' big league club out of Spring Training. In 16 appearances, he has a 0.52 ERA with 21 strikeouts in 17 1/3 innings, and he has held opponents scoreless in 15 of those games.

"His stuff is unbelievable," Stephenson said. "It’s attacking the zone and forcing guys to hit it. It’s almost like he got better against Ramírez when the moment was bigger for him."

Bell has gradually given Díaz more higher-leverage situations as he's earned them. Especially with veteran Lucas Sims on the injured list, the Reds will need Díaz to step up.

“I’m going to be ready for any situation that the manager tells me that I should be ready," Díaz said.

Díaz is the younger brother of Mets closer Edwin Díaz, and the two are in contact daily, talking about the game. Edwin often offers advice after watching his brother pitch on video. Alexis Díaz had not been in touch yet with Edwin after the game.

"I know soon enough, we’ll get in touch and [he’ll] be really excited for me too," he said.