Mark Wahlberg is diving head-first into his Houston Astros fandom ... going as far as to say he'd donate one of his thumbs to help superstar Jose Altuve get back from his injury!!
The 51-year-old actor is usually a Boston Red Sox fan, but has been supporting the 'Stros due to their ability to wreck the New York Yankees lately. Mark has been welcomed to the H-Town fanbase with open arms ... and even gave the ceremonial "Play Ball!!!" call at Thursday's Opening Day game against the Chicago White Sox.