ST. PETERSBURG -- Making history is becoming routine for Gavin Williams just 10 starts into his Major League career. 

On the heels of a sublime outing against the Blue Jays on Monday, the Guardians’ rookie right-hander looked arguably better as he overpowered the Rays through five innings in Cleveland’s 6-5 loss at Tropicana Field on Saturday.

His 10 strikeouts will grab the headlines. But after issuing 22 walks through his first 49 2/3 innings, Williams did not allow a free pass to Tampa Bay, becoming just the second rookie pitcher in franchise history (since 1894) to record double-digit strikeouts without a walk in a start.

“I think Gavin is maturing right in front of our eyes,” said manager Terry Francona.

“I’m definitely getting into a groove,” Williams said. “I know my stuff plays right here. Just keep going with it.”

Facing the club that selected him out of high school in the 30th round of the 2017 MLB Draft, Williams ran up just three three-ball counts while pounding the zone with fastballs. He threw his heater a season-high 64 percent of the time and tied his season best with 14 swings and misses off it. The Rays went 2-for-12 with seven K’s against Williams’ best offering.

But we saw some of that aforementioned maturation, as Williams mixed in his 55-grade curveball on a season-high 23 percent of his pitches and more than twice as often as his slider, which had been his second-most-frequent pitch entering the game.

“I think he was kind of throwing a lot of good heaters at the top of the zone for strikes and just tunneling the curveball off of that,” catcher Cam Gallagher said. “Every time I catch him, every time he goes out there, he keeps getting better and better. I think it’s just the confidence he’s getting and just familiarity with the league.”

That confidence was on display in two at-bats against Rays star shortstop Wander Franco. Franco crushed a walk-off homer against Cleveland in Friday’s series opener, and he came into this game with 14 hits in his past 24 at-bats before singling in the first inning off one of Williams’ two changeups.

Franco also has done lots of damage against fastballs, holding a .333 average and a .590 slugging percentage against them prior to Saturday.

No matter. Williams went after Franco in the third inning with four fastballs in a five-pitch at-bat that ended with a 97.9 mph pitch getting past his bat on the inner half of the strike zone.

That was Franco’s first strikeout in 29 plate appearances, and it came during a stretch in which Williams recorded seven consecutive outs on K’s.

The pair matched up again in the bottom of the fifth inning, and Williams began by yanking a slider toward Franco’s left hip. The rookie admitted that he “messed it up,” but it still garnered a swing from Franco reminiscent of something you might see on a golf course.

From there, it was power vs. power. After getting ahead 1-2, Williams fired a pitch at 99.1 mph that Franco fouled off. He then blew a high fastball past a flailing Franco at 98.3 mph.

Those two pitches -- Williams' final two in this 87-pitch start -- accounted for his fastest pitch and his fastest pitch on a strikeout, respectively, during his young MLB career.

“I know the scouting report on him. I know my stuff, and I think it was a good game plan,” Williams said.

As Williams let out a primal scream as he spun off the mound, Francona had a decision to make: Let him go back out for the sixth, or call it a night. He chose the latter.

“I told him, ‘I know you can go back out,’” Francona said. “I’ve just got an obligation to keep an eye on this kid because he’s going to be a big part of this future.”

A solo homer by Luke Raley was the only scoring Tampa Bay mustered against the burgeoning ace, who permitted five hits.

Cleveland posted 13 hits despite being without José Ramírez while he serves a two-game suspension. It helped the Guardians gain a 5-3 advantage heading to the bottom of the ninth. But Tampa Bay scored three runs on four hits and a wild pitch against closer Emmanuel Clase, who was tagged with his ninth blown save.

The Guardians suffered a walk-off loss, just as they did Friday. Williams was left with a no-decision, just as he was against Toronto five days earlier. But after yet another impressive performance, one can wonder what kind of history Williams will author the next time he takes the mound.

“I know it hurts today, but he’s on the right track,” Francona said.