The Tampa Bay Rays (57-59) and Seattle Mariners (63-53) begin a 3-game series Friday. First pitch from T-Mobile Park in Seattle is set for 9:40 p.m ET. Let’s analyze BetMGM Sportsbook’s MLB odds around the Rays vs. Mariners odds and make our expert MLB picks and predictions for the best bets.

Season series: First meeting; tied 3-3 last season

The Rays opened their challenging 4-city, 12-game West Coast road trip with a 2-1 series win over the Los Angeles Angels, capping it with a 5-4 victory Wednesday as -116 road favorites while pushing on the 9-run total. All-Star 3B Junior Caminero fueled the offense with 2 home runs, but it was DH Christopher Morel who delivered the decisive blow—a go-ahead homer in the top of the seventh inning.

The Mariners completed a 3-game sweep of the White Sox on Wednesday, earning a 4-3 extra-inning win as heavy -278 home favorites while pushing on the 7-run total. LF Randy Arozarena went 2-for-5 with a 2-run homer, and RF Dominic Canzone won it with a walk-off single in the 11th. Seattle has now won 4 straight games and 7 of its last 11 contests.

Rays at Mariners projected starters

RHP Drew Rasmussen vs. RHP Luis Castillo

Rasmussen (9-5, 2.81 ERA) is making his 23rd start. He has a 1.02 WHIP, 2.1 BB/9 and 7.9 K/9 through 105 2/3 innings.

Last start: Win, 5 1/3 IP, 0 ER, 4 H, 0 BB, 6 K in 4-0 victory against the Los Angeles Angels Saturday2025 road stats: 4-0, 3.34 ERA (35 IP, 13 ER), 1.11 WHIP, 7.7 K/9 in 8 startsCareer vs. Mariners: 2-0, 0.61 ERA (14 2/3 IP, 25 ER), 0.82 WHIP, 12.3 K/9 in 4 games (3 starts); last start in 2024

Castillo (8-6, 3.22 ERA) is making his 24th start. He has a 1.21 WHIP, 2.5 BB/9 and 7.9 K/9 through 131 1/3 innings.

Last start: No-decision, 4 1/3 IP, 2 ER, 4 H, 1 BB, 4 K in 6-4 loss against the Texas Rangers Saturday2025 home stats: 4-4, 2.40 ERA (75 IP, 20 ER), 1.04 WHIP, 8.6 K/9 in 13 startsCareer vs. Rays: 2-1, 3.30 ERA (30 IP, 11 ER), 1.23 WHIP, 9.0 K/9 in 5 starts; last start in 2024

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Rays at Mariners odds

Provided by BetMGM Sportsbook; access USA TODAY Sports Scores and Sports Betting Odds hub for a full list. Lines last updated Thursday at 11:32 p.m. ET.

Moneyline (ML): Rays +105 (bet $100 to win $105) | Mariners -125 (bet $125 to win $100)Run line (RL)/Against the spread (ATS): Rays +1.5 (-200) | Mariners -1.5 (+170)Over/Under (O/U): 7.5 (O: +100 | U: -120)Rays at Mariners picks and predictionsPrediction

Mariners 4, Rays 2

BET MARINERS (-125).

Both teams enter Friday night’s series opener playing strong baseball, which explains the tight moneylines. Still, the edge goes to the Mariners at home. Seattle has posted a stellar 3.40 team ERA at T-Mobile Park this season, fourth-best in MLB, and has been even sharper lately with a 3.10 ERA over the last 15 days—third-best in the league. That dominant pitching has fueled their 6 wins in the last 7 games.

Castillo has been a steady force, going 4-1 over his last 6 starts while allowing just 9 earned runs in 35 innings. At home, he’s been even better, giving up only 5 earned runs in his last 4 starts (23 IP). While Tampa Bay’s Rasmussen has also pitched well, the Rays are just 25-29 on the road compared to Seattle’s 34-25 mark at home.

With momentum, pitching form, and a division race heating up—Seattle is just 1 1/2 games behind the NL West-leading Houston Astros—the Mariners look like the safer bet to open the series with a win.

PASS.

I do not like the odds on the run line, I’d rather take slightly worse odds for the Mariners to just win outright than worrying about covering.

UNDER 7.5 (-120).

The Under has been the trend in recent matchups between the Rays and Mariners, going 2-1-1 over the last 4 meetings. It’s also 4-1-1 in Tampa Bay’s last 6 games and has cashed in each of Rasmussen’s last 3 starts. While the Over is 4-0-1 in Seattle’s last 5, those came against weaker teams like the White Sox. With both clubs capable of limiting damage, this matchup sets up for a low-scoring affair.

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