All signs point to a pitchers' duel when the Texas Rangers open a three-game series against the Seattle Mariners on Friday in Arlington, Texas.

Both starters -- Rangers right-hander Jon Gray (5-1, 2.81 ERA) and Mariners righty Luis Castillo (4-2, 2.69) -- rank among the top 15 ERA leaders in baseball.

Gray will make his 11th start of the season. He threw seven innings of one-run ball in his previous start, a 12-2 victory over the Baltimore Orioles on May 26. Gray also threw seven innings of one-run ball in leading the Rangers to a 2-1 victory over the Mariners in Seattle on May 8.

In six career starts against the Mariners, Gray is 2-2 with a 4.67 ERA.

The Rangers handed Castillo his first loss of the season when they last met. Texas won 4-3 on May 10 as Castillo gave up three runs on eight hits over five innings. That was the only career appearance Castillo has made against the Rangers.

But Castillo, who will make his 12th start Friday, has found his groove of late. He's thrown six shutout innings in both of his past two starts. That includes an impressive outing Saturday in which he threw six scoreless innings with one hit and 10 strikeouts in a 5-0 victory over Pittsburgh.

"Luis Castillo is getting back on a roll," Seattle manager Scott Servais said after the Pittsburgh gem. "It was awesome today after that first hit of the game. He got after it, just super aggressive.

"I can't say enough about what he means to our pitching staff and what he's done since he's been here."

Servais went on to describe Castillo as "super competitive."

That's a good thing, especially as the Mariners open a series against the American League West's top team entering June.

The Rangers went 18-9 in May, which was the team's highest win percentage in any month since going 20-8 (.714) in June 2016. They're coming off a nine-game road trip in which they won the series at all three stops: Pittsburgh, Baltimore and Detroit.

"It was great to see," Texas manager Bruce Bochy said. "This trip was maybe the toughest of all the trips with the day games after night games. ... It was not an easy trip. To take the series in every city, that was really good baseball. I was proud of these guys that came out every day."

Texas has several players getting it done on the offensive end with Marcus Semien, Leody Taveras, Josh Jung and Nathaniel Lowe all impressing in May. All four of those hitters surpassed the 30-hit mark last month.

For Seattle of late, outfielder Julio Rodriguez remains a bright spot with three home runs in his past six games.

This is the second series between the teams this season after Texas went 2-1 in a three-game series at Seattle from May 8-10. Last season, Seattle went 14-5 against Texas, including a 7-3 mark at Globe Life Field.