The AL West pennant chase will heat up at Daikin Park on Thursday when the Houston Astros host the Seattle Mariners in the opener of an extended series. The M's hold a slim 2-1 lead in the 2025 rivalry after taking two of three from their division rivals at Safeco in early April.George Kirby will be making his highly anticipated season debut for the Mariners against an opponent he's dominated in the past. The same goes for Lance McCullers Jr., who has had a rough go since returning from the IL in early May.Mariners vs. Astros recent form and recordsSeattleEven with the starting staff dropping like flies, the Mariners continue to get the job done. Winners in six of its last eight games, Seattle currently sits in the catbird seat of the AL West, 3.5 games up on the Astros.Dan Wilson's troops have proven to be enormous boons to MLB bettors' bankrolls, ranking out as the league's second most profitable team behind only the Detroit Tigers. Most impressively, the bulk of their $642 return has come on the road, where they sit six games over .500 at 15-9.HoustonWith the departure of Alex Bregman this past offseason, Houston has found it incredibly tough to find any traction. The injury bug hasn't been kind to Joe Espada's roster either, with a number of notable names situated on the IL.Even so, Houston still finds itself in the thick of the AL West pennant chase, 3.5 games back of Seattle with a 25-24 record. The team is $190 in the red overall for its backers, but has been a lucrative investment at home, where a 15-9 overall record has amounted to a $312 rate of return.InjuriesSeattleLuke Raley RF 10 Day IL - SideBryce Miller SP 15 Day IL - ElbowTrent Thornton RP 15 Day IL - StomachLogan Gilbert SP 15 Day IL - ForearmGregory Santos RP 60 Day IL - KneeVictor Robles RF 60 Day IL - ShoulderRyan Bliss 2B 60 Day IL - BicepsJackson Kowar RP 60 Day IL - ElbowHoustonYordan Alvarez LF 10 Day IL - HandTaylor Trammell LF 10 Day IL - CalfPedro Leon RF 10 Day IL - KneeSpencer Arrighetti SP 15 Day IL - ThumbLuis Garcia SP 60 Day IL - ElbowCristian Javier SP 60 Day IL - ElbowJ.P. France SP 60 Day IL - ShoulderHayden Wesneski RP 60 Day IL - ElbowStarting PitchersGeorge Kirby (14-11, 3.53 ERA in 2024)Allowed 181 hits (22 HR) & 75 ER with a 179:23 K/BB ratio in 33 2024 starts.3-0 with a 1.55 ERA & 37:4 K/BB ratio in 40.2 career IP thrown vs. the Astros.8-6 with a 3.89 ERA and 95:13 K/BB ratio in 108.2 IP on the road in 2024.Lance McCullers Jr. (0-1, 7.88 ERA in 2025)Allowed 10 hits (1 HR) & 7 ER with a 6:7 K/BB ratio in three 2025 appearances.Worked 4.0 IP of 4 hit (0 HR) 0 ER ball with 2:1 K/BB ratio at Rangers last start.10-3 with a 2.80 ERA & 120:42 K/BB ratio in 103.0 career IP thrown vs. Mariners.0-1 with a 189.00 ERA and 0:3 K/BB ratio in 0.1 IP at home in 2025.Must-Watch HittersSeattleRandy Arozarena hasn't ignited the Mariners' offense quite like upper management envisioned when making the move to get him in Seattle by last year's trade deadline. He's slashing .224/.360/.394/.754 with six home runs and 21 RBIs over 165 at-bats.However, his bat has seen Lance McCullers Jr.'s stuff really well in the past. He's 5-for-11 lifetime with a home run. After going hitless at Chicago, look for him to get back on track with the short porch in left calling his name.HoustonYordan Alvarez is the only player currently on the Astros' roster who's tallied an extra base hit against George Kirby. Pickings are slim here with the Mariners right-hander dominating this lineup in the past.However, tonight marks his season debut, which means he might not be long for his start in an attempt to dip his toe back into the MLB waters. Isaac Paredes has been a steady bat recently, hitting safely in six straight games with four home runs and nine RBIs. All his damage has been done against righties, so take a shot on him remaining hot.Mariners vs. Astros MLB 2025 Betting OddsThursday 5/22Money LineRun LineTotal RunsSeattle Mariners-135-1.5 +120O 8.5 -110Houston Astros+114+1.5 -142U 8.5 -110Mariners vs. Astros expert picks and game predictionThis will be an emotional outing for Lance McCullers Jr., who will retake his home bump after a disastrous debut against the Cincinnati Reds on May 10, when he served up seven earned runs in just 0.1 innings. To make matters worse, the former World Series champion received death threats from overzealous Astros fans in the aftermath.It's been a tough road back for the right-hander as he continues to recover from over two years of tendon surgeries. But if there's ever a moment for a storybook chapter in his comeback, it's tonight—with his teammates looking to chip away at their divisional deficit as home underdogs, according to DraftKings Sportsbook.Mariners vs. Astros Prediction: Houston Wins 5-4