MLB: Seattle Mariners at Tampa Bay Rays Odds & Prediction

Game Info: Monday, September 1, 2025, 7:35 PM ET, George M. Steinbrenner Field, Tampa, FL

The Mariners are off to Tampa for a crucial Labor Day matchup with the Rays, kicking off a three-game series that could impact the playoff race in both leagues. Seattle is vying for a Wild Card spot, while Tampa is trying to stay afloat in the AL East, which makes this game really important and it opens up some betting opportunities.

Betting Odds

Moneyline: Mariners -122 | Rays +104

Run Line: Mariners -1.5 (+128) | Rays +1.5 (-154)

Total: 8.5 (O/U -110)

Seattle starts off as a slight favorite on the road, mainly because of their pitching advantage and how they’ve been playing lately. The over/under is set at 8.5, which seems pretty accurate considering the inconsistency of both teams’ offenses.

Mariners Betting Preview

Seattle (73-64) is heading to Tampa feeling pretty good after taking two out of three games from Cleveland over the weekend. Luis Castillo is set to pitch, and while his 3.75 ERA isn’t the most impressive, he’s been reliable, especially against AL East teams. In six career matchups, Castillo has held Rays hitters to a .200 average, and his strikeout skills really stand out in the pitcher-friendly Steinbrenner Field.

The Mariners are all about their offense and hitting those home runs. Cal Raleigh is having an awesome season with 50 home runs and 107 RBIs, and Julio Rodríguez is getting hot again, hitting .333 in his last 10 games. Seattle is in the top five for home runs and has managed to cover the run line in 7 out of their last 10 away games.

Rays Betting Preview

Tampa Bay (67-69) is just hanging in there in the AL East and really needs to take this series. Shane Baz is pitching, but he’s been struggling lately. He’s allowed 14 earned runs over his last three games and has had some control problems. Going up against a solid Mariners lineup, that’s definitely something to worry about.

The Rays surely pack a punch offensively. Junior Caminero (39 HR, 94 RBI) and Yandy Díaz (.284 AVG) head a lineup that can rack up runs quickly. On the flip side, Tampa’s bullpen has struggled with consistency, converting just 56% of their save chances and blowing leads in 3 of their last 6 games.

Matchup & League Facts

The Mariners have scored 6 victories in their last 10 matchups with the Rays.

Seattle has gone over the total in 6 out of their last 10 games.

The Rays hold a 1-2 record as underdogs in their last 4 contests.

Castillo boasts a career ERA of 3.16 when facing Tampa.

The Mariners are 3rd in the MLB for home runs, while the Rays sit at 13th in runs scored per game.

At first look, this matchup appears to favor Seattle, particularly with Castillo on the mound and the Mariners hitting well. Tampa’s bullpen has some problems, and Baz’s unpredictability makes it hard to support the home team with any confidence.

Mariners at Rays Prediction

I’m rooting for the Mariners in this matchup. They’ve got a better starting pitcher, a more exciting lineup, and they’ve been doing great away from home. The total is a little tricky, but given Baz’s recent form and Seattle’s offensive power, betting on the over looks like a solid choice.

Sportbook.AG Final Prediction: Pick: Mariners ML (-122) Lean: Over 8.5