The Seattle Mariners and Boston Red Sox meet again at Fenway Park on Tuesday, one night after a 10-inning game that emptied both bullpens. Boston sits at -126 on the moneyline, exactly where it opened, even though the public is piled on the Red Sox. The total has fallen a full run. Our headline play comes from what this market has refused to do.
Last Updated: Tuesday, September 1, 2026
Seattle Mariners vs. Boston Red Sox — Time & How to Watch
| Where | Fenway Park, Boston, Massachusetts |
| When | Tuesday, September 1 – 6:45 PM ET |
| TV | NESN (Boston), Mariners.TV (Seattle) |
Seattle Mariners vs. Boston Red Sox Betting Preview
Seattle hands the ball to right-hander Bryan Woo, who is 9-9 with a 4.36 ERA over 25 starts. His peripherals read better. Woo has 142 strikeouts against 30 walks in 142.1 innings, a 1.10 WHIP. However, his workload has changed. He threw 91 to 95 pitches in four straight starts through August 11. Since then he has been capped at 75 and 76 pitches, with 10 days between those outings. His August 26 start was rough: four innings, six earned runs.
Boston has not named a starter. The Red Sox are still listed as TBD on the league’s probable pitchers page, with Patrick Sandoval set for Wednesday. An opener, a spot starter, or a bullpen game are all possible. That is a meaningful gap when the starter is the biggest variable. Boston is 75-63 and holds the second wild card. Seattle is 64-74, six games back in the AL West.
Form favors the home side. Boston is 6-4 in its last 10 and won Monday’s opener 9-8 in extras. Seattle has lost five straight while scoring 2.40 runs per game. Still, the Red Sox lost their best bat Monday, when Willson Contreras went on the 10-day injured list with a hamstring strain. He was hitting .274/.384/.516 with 26 home runs. Roman Anthony and Trevor Story came off the injured list on August 30, so this lineup is changing in both directions.
Seattle Mariners vs. Boston Red Sox Odds
| Run Line | Moneyline | Total | |
|---|---|---|---|
| Mariners | +1.5 (-225) | +106 | U 7.5 (-125) |
| Red Sox | -1.5 (+185) | -126 | O 7.5 (+105) |
Odds accurate as of Tuesday, September 1, 2026 via TheSpread.com. Odds change, get the latest MLB Odds – Futures – Props
Seattle Mariners vs. Boston Red Sox — Who Is the Public Betting?
| Mariners | 35% | 65% | Red Sox |
See the latest MLB Public Betting Splits and make smarter wagers!
Mariners vs. Red Sox Prediction — Will Seattle End Skid?
Start with the market. Boston opened at -126 on the moneyline and is still -126. Meanwhile, 81% of moneyline tickets have landed on the Red Sox. A number backed that heavily usually drifts toward -140. This one has not moved a cent. A frozen line under lopsided public support is the classic footprint of money arriving on the quieter side.
The run line points the same way. Boston opened at -1.5 (+170) and now sits at -1.5 (+185). That is a move away from the popular side, even though 65% of run-line bets are on the Red Sox. Some of that repricing simply tracks the lower run expectation. The baseball supports the skepticism, though. Boston has no announced starter, owns a .715 OPS against right-handed pitching, and is missing its most productive hitter.
The case against is real. Seattle is 27-43 on the road, and its bullpen has been the worst in baseball this month. Boston’s relief corps ranks second in MLB at 3.14, so a bullpen game frightens the Red Sox less than most clubs. This is a lean on price and market signal, not a claim that Seattle is the better team. At a near-even number, the underdog only needs to be closer than the tickets suggest.
The Pick: Seattle Mariners Moneyline (+106)
Mariners vs. Red Sox Prediction — Is the Total too Short?
Handicap this total from the back of the game forward. Seattle’s bullpen posted a 7.87 ERA across 90.1 innings in August, the worst mark in the majors by a wide margin. Those arms are likely to be needed early. Woo has not exceeded 76 pitches in his last two starts, so five innings is the reasonable expectation. Boston’s unnamed starter points the same way, since an opener means several relievers rather than one deep outing. Fenway also inflates doubles well above league average.
In contrast, the market has moved hard the other way. The total opened at 8.5 and now sits at 7.5, with the under juiced from -115 to -125. Fading a full run of one-directional movement is uncomfortable. The under case is coherent too. Both offenses have been quiet, Woo’s walk rate is excellent, and Boston’s bullpen is genuinely good. The counter is that the value in the under sat at 8.5, not here.
The Pick: Over 7.5 (+105)
Final Thoughts and Bonus Angle
Both plays rest on the same load-bearing fact. Woo’s pitch count shapes the side and the total at once. If he holds a lead into the sixth, the moneyline improves and the over suffers. If he exits after four, the reverse applies. Watch his count as the order turns a third time, and watch whether Boston opens with a reliever. No third angle stands on its own tonight without recycling that reasoning.
For more on this series, see Monday’s Mariners vs. Red Sox prediction and our latest MLB best bets coverage. To recap the card: Seattle Mariners Moneyline (+106) and Over 7.5 (+105).
MLB Mariners vs. Red Sox FAQ: Tuesday September 1, 2026
What time does the Mariners vs. Red Sox game start?
First pitch is 6:45 PM ET on Tuesday, September 1, 2026, at Fenway Park in Boston. This is the middle game of a three-game series between the Seattle Mariners and Boston Red Sox. The opener went 10 innings on Monday, and the finale follows on Wednesday.
What channel is the Mariners vs. Red Sox game on?
The game airs on NESN in the Boston market and on Mariners.TV in the Seattle market. There is no national television broadcast scheduled, so viewers outside those two regions need an out-of-market package. Radio coverage runs on WEEI in Boston and Seattle Sports 710 AM.
Who is pitching for the Mariners tonight?
Right-hander Bryan Woo starts for Seattle. He carries a 9-9 record with a 4.36 ERA, a 1.10 WHIP, and 142 strikeouts against 30 walks in 142.1 innings across 25 starts. Boston had not announced its starter as of publication and remains listed as TBD.
Who won the last meeting between the Mariners and Red Sox?
Boston won 9-8 in 10 innings on Monday, August 31, 2026, at Fenway Park. Trevor Story delivered a bases-loaded RBI single in the 10th. The result was Seattle’s fifth straight loss and gave Boston a 3-1 edge in the season series.
Where do the Mariners and Red Sox stand in their divisions?
Seattle is 64-74 and sits third in the AL West, 6.0 games behind Houston. Boston is 75-63 and sits third in the AL East, 7.5 games behind Tampa Bay. The Red Sox do hold the second American League wild card spot, and both marks reflect games through August 31.