The Houston Astros have held Baltimore without a hit through six innings Monday night, with Jake Odorizzi pitching the first five and the bullpen trying to complete a combined no-hitter.

Odorizzi retired his first 13 batters before walking DJ Stewart on a full count. That was the only baserunner for the Orioles. Houston leads 7-0 heading into the bottom of the seventh.

Cristian Javier retired Baltimore in order in the sixth. Pedro Severino hit a sharp line drive to left field, but it was right at Houston's Yordan Alvarez.

Houston Astros starting pitcher Jake Odorizzi has his belt inspected by first base umpire Ted Barrett (65) and home plate umpire Angel Hernandez, right, during the first inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

Houston Astros starting pitcher Jake Odorizzi has his belt inspected by first base umpire Ted Barrett (65) and home plate umpire Angel Hernandez, right, during the first inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

In a season when pitchers have dominated — and on the day umpires began checking them for illegal foreign substances — Odorizzi didn't seem the least bit bothered. He struck out nine and threw 86 pitches, three shy of his season high.

The 31-year-old Odorizzi missed more than a month with a strained muscle in his right arm. This was his fifth appearance and fourth start since returning.

Houston was looking to pitch the seventh no-hitter in the majors this season. That would match 1990, 1991, 2012 and 2015 for the most since 1900, one shy of the record eight in 1884 — the first season overhand pitching was allowed.

Houston Astros starting pitcher Jake Odorizzi (17) has his glove inspected by first base umpire Ted Barrett, left, and home plate umpire Angel Hernandez during the first inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

Houston Astros starting pitcher Jake Odorizzi (17) has his glove inspected by first base umpire Ted Barrett, left, and home plate umpire Angel Hernandez during the first inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

It would be the first combined no-hitter of the season. The others were thrown by San Diego’s Joe Musgrove, Carlos Rodón of the Chicago White Sox, Baltimore’s John Means, Cincinnati's Wade Miley, Detroit’s Spencer Turnbull and the New York Yankees’ Corey Kluber.

In addition, Arizona’s Madison Bumgarner had a seven-inning hitless game in a doubleheader on April 25 that is not recognized as a no-hitter by Major League Baseball.

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Houston Astros assistant pitching coach Bill Murphy, left, looks on as relief pitcher Cristian Javier has his gear inspected by first base umpire Ted Barrett, back left, and home plate umpire Angel Hernandez during the sixth inning of a baseball game, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

Houston Astros assistant pitching coach Bill Murphy, left, looks on as relief pitcher Cristian Javier has his gear inspected by first base umpire Ted Barrett, back left, and home plate umpire Angel Hernandez during the sixth inning of a baseball game, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

 Houston Astros starting pitcher Jake Odorizzi, left, holds his hat and glove to present to first base umpire Ted Barrett for inspection during the fourth inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)

Houston Astros starting pitcher Jake Odorizzi, left, holds his hat and glove to present to first base umpire Ted Barrett for inspection during the fourth inning of a baseball game against the Baltimore Orioles, Monday, June 21, 2021, in Baltimore. (AP PhotoJulio Cortez)