The Houston Astros swooped for Arizona pitcher Zack Greinke on Wednesday in a blockbuster deal agreed just minutes before Major League Baseball’s trade window slammed shut.

Multiple US media outlets reported that Diamondbacks ace Greinke, a six-time All-Star and former Cy Young Award winner, was heading to Houston in exchange for a raft of top prospects.

Greinke, 35, boasts a 2.90 ERA this season with 10 wins and four losses from 23 starts.

His arrival in Houston gives the 2017 World Series champions another heavyweight starting pitcher to set alongside Justin Verlander and Gerrit Cole.

The Astros are currently top of the American League West division with 69 wins against 39 losses.

There was no immediate confirmation of the deal from the Astros or Diamondbacks.

If confirmed, Greinke’s move looked set to be the biggest of a low-key trading window.

Despite frenzied speculation prior to the trade deadline, neither the New York Yankees nor the Los Angeles Dodgers strengthened their pitching with an elite-level signing.

The San Francisco Giants, meanwhile, who have surged into wild card contention in the National League West, held on to three-time World Series champion pitcher Madison Bumgarner and highly rated reliever Will Smith.

Elsewhere on Wednesday, the Cleveland Indians confirmed pitcher Trevor Bauer has been traded to the Cincinnati Reds as part of a deal that sends Yasiel Puig heading in the opposite direction.

Bauer, who angered Indians manager Terry Francona on Sunday after hurling a baseball over centre field in frustration, joins the Reds after six years in Cleveland.

Under the three-team move, the Reds’ Cuban outfielder Puig and minor league pitcher Scott Moss will move to Cleveland.

The San Diego Padres are sending outfielder Franmil Reyes, left-handed pitcher Logan Allen and outfielder Victor Nova to the Indians.

Reds outfielder Taylor Trammell heads to San Diego as part of the deal.

Bauer and Puig’s moves come after recent controversy involving both players.

Bauer irked Francona on Sunday after hurling a pitch into centre field in disgust.

Puig’s last act for the Reds, meanwhile, saw him pile into a mass brawl on Tuesday in a clash with the Pittsburgh Pirates.