The Oakland Athletics and Seattle Mariners will begin a four-game series on Thursday night. It's time to continue our MLB odds series and make an Athletics-Mariners prediction and pick.

This is an absolutely crucial series for both teams. The Athletics are hot on the heels of the Houston Astros, trailing the AL West lead by only 3.5 games. That division title is surprisingly still in reach for the Mariners, too, as they're only 6.5 games back from Houston. The winner of this series will come out in pretty good position to make a run at the Astros, so it will be an incredibly competitive series. This is about as important of a series as you can get in July, so this should be an exciting opener.

Here's how the bookmakers have set the lines for Thursday's game.

MLB Odds: Athletics-Mariners Odds

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Oakland Athletics ML (-141)

Seattle Mariners ML (+130)

Over 7 1/2 runs (-113)

Under 7 1/2 runs (-107)

Why The Athletics Could Win

The Athletics have been winning games because of their strong pitching rotation. They'll deploy one of their stronger starters in Sean Manaea for Thursday's opener.

Manaea owns a 3.28 ERA and a 1.20 WHIP on the year. Manaea has faced the Mariners once this season, and it ended pretty well for him. Manaea pitched a complete game and didn't allow a run.

The Mariners are also significantly worse offensively when they play at home. Their batting average drops from .234 on the road to .204 when at home. Seattle is also a little bit worse against right-handed pitching, seeing a small drop in batting average when facing a righty.

Opposing pitcher Chris Flexen is in the middle of putting together a pretty nice season for himself, but the Athletics have been a problem for him in the past. He has faced them once this season, allowing five runs over six innings. It's unreasonable to expect the A's to hit him as well as they did last time, but it's encouraging to know that Oakland can hit Flexen well.

Why The Mariners Could Win

The Mariners have the privilege of sending one of the hottest pitchers in baseball to the mound. Chris Flexen will take the ball for Thursday's start, something that usually works out well for Seattle.

Flexen has been good all season long, but his recent stretch of starts has been spectacular. Over his last seven starts, Flexen has earned a 1.77 ERA and a 0.94 WHIP. His presence on the mound gives the Mariners a chance at beating anyone, so knocking off the Athletics is certainly possible.

To make things a little bit easier for Flexen, the A's struggle against right-handed pitching. All of their major batting stats fall a little bit when facing a righty as opposed to a lefty.

Final Athletics-Mariners Prediction & Pick

I think the Athletics will take the first game of this series, but they aren't the best bet on the board. The under looks great here and gives better odds than a straight-up bet on the Athletics. With two great starters on the mound and two very mediocre offenses, the under should be safe.

FINAL PICK: Under 7 1/2 runs (-107)