Astros vs Mariners Prediction, Odds, Moneyline, Spread & Over/Under for Sept. 20

Odds updated as of 6:12 a.m.

The Houston Astros versus the Seattle Mariners is on the MLB schedule for Saturday.

Before you do any MLB betting on this matchup at FanDuel Sportsbook, here's what you need to know.

Astros vs Mariners Game Info

• Houston Astros (84-70) vs. Seattle Mariners (85-69)
• Date: Saturday, September 20, 2025
• Time: 7:10 p.m. ET
• Venue: Daikin Park -- Houston, Texas
• Coverage: SCHN and ROOT Sports NW

Astros vs Mariners Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: HOU: (-116) | SEA: (-102)
• Spread: HOU: +1.5 (-192) | SEA: -1.5 (+155)
• Total: 8 -- Over: (-100) | Under: (-122)

Astros vs Mariners Probable Starting Pitchers

Probable Pitchers: Framber Valdez (Astros) - 12-10, 3.59 ERA vs George Kirby (Mariners) - 9-7, 4.46 ERA

The Astros will give the ball to Framber Valdez (12-10, 3.59 ERA), who is eyeing win No. 13 on the season, and the Mariners will turn to George Kirby (9-7, 4.46 ERA). Valdez and his team are 11-17-0 ATS this season when he starts. Valdez's team has been victorious in 52.2% of the games he's started as the moneyline favorite with a record of 12-11. When Kirby starts, the Mariners are 8-11-0 against the spread. The Mariners were the moneyline underdog for two Kirby starts this season -- they split the games.

Astros vs Mariners Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Astros win (51.8%)

Astros vs Mariners Moneyline

• Seattle is a -102 underdog on the moneyline, while Houston is a -116 favorite at home.

Astros vs Mariners Spread

• The Mariners are 1.5-run favorites against the spread for this matchup with the Astros. The Mariners are +155 to cover, while the Astros are -192 to cover as a 1.5-run underdog on the runline.

Astros vs Mariners Over/Under

• The over/under for the Astros versus Mariners game on Sept. 20 has been set at 8, with -100 odds on the over and -122 odds on the under.

Bet on Houston Astros vs. Seattle Mariners on FanDuel today!

Astros vs Mariners Betting Trends

• The Astros have come away with 50 wins in the 94 contests they have been listed as the favorites in this season.
• Houston has a record of 47-42 in contests when oddsmakers favor them by -116 or more on the moneyline.
• Contests with the Astros have gone over the total set by sportsbooks in 69 of 153 chances this season.
• The Astros are 77-76-0 against the spread in their 153 games with a line set by sportsbooks this season.
• The Mariners have an 18-21 record in games they were the underdog on the moneyline (winning 46.2% of those games).
• Seattle is 17-17 (winning 50% of its games) when it has played as a moneyline underdog of -102 or longer.
• The Mariners have had an over/under set by bookmakers 149 times, and have combined with opponents to go over the total in 80 of those games (80-64-5).
• The Mariners have collected a 66-83-0 record ATS this season.

Astros Player Leaders

• Jose Altuve leads Houston with a slugging percentage of .441, fueled by 49 extra-base hits. He has a .261 batting average and an on-base percentage of .322.
• Among qualified batters in MLB, his batting average ranks 61st, his on-base percentage ranks 87th, and he is 67th in slugging.
• Jeremy Pena has 148 hits and an OBP of .361 to go with a slugging percentage of .470. All three of those stats lead Houston hitters this season. He's batting .303.
• Among qualifying batters, he ranks sixth in batting average, 18th in on-base percentage and 40th in slugging percentage.
• Yainer Diaz is batting .256 with a .416 slugging percentage and 68 RBI this year.
• Carlos Correa is batting .276 with a .330 OBP and 50 RBI for Houston this season.
• Correa heads into this game on a four-game hitting streak. During his last five outings he is batting .300 with two doubles and a walk.

Mariners Player Leaders

• Cal Raleigh has 139 hits with a .360 on-base percentage, leading the Mariners in both statistics. He's batting .246 and slugging .583.
• Including all qualifying hitters in MLB, his batting average places him 99th, his on-base percentage is 21st, and he is third in slugging.
• Julio Rodriguez's .479 slugging percentage paces his team. He has a batting average of .269 with an on-base percentage of .321.
• He ranks 40th in batting average, 91st in on-base percentage and 32nd in slugging percentage in the majors.
• Josh Naylor is batting .289 with 26 doubles, a triple, 20 home runs and 47 walks.
• Eugenio Suarez has 26 doubles, 47 home runs and 44 walks while hitting .228.

Astros vs Mariners Head to Head

• 9/19/2025: 4-0 SEA (Favorite: Astros, Spread: -1.5, Total: 7.5, Favorite Moneyline: -108, Underdog Moneyline: -108)
• 7/20/2025: 11-3 HOU (Favorite: Mariners, Spread: -1.5, Total: 6.5, Favorite Moneyline: -144, Underdog Moneyline: +122)
• 7/19/2025: 7-6 SEA (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -132, Underdog Moneyline: +112)
• 7/18/2025: 6-1 SEA (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 5/25/2025: 5-3 HOU (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -138, Underdog Moneyline: +118)
• 5/24/2025: 2-1 HOU (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -110, Underdog Moneyline: -106)
• 5/23/2025: 5-3 SEA (Favorite: Astros, Spread: -1.5, Total: 8.5, Favorite Moneyline: -116, Underdog Moneyline: -102)
• 5/22/2025: 9-2 HOU (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -132, Underdog Moneyline: +112)
• 4/9/2025: 7-6 SEA (Favorite: Astros, Spread: -1.5, Total: 7.5, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 4/8/2025: 2-1 HOU (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -120, Underdog Moneyline: +102)

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