After going head-to-head at the box office, "Captain America" star Chris Evans and Guardian of our Galaxy Chris Pratt have agreed to a charitable bet over Super Bowl XLIX.

It's root, root, root for the home team, as they say, and so Boston native Evans has taken up his signature red, white and blue in support of the New England Patriots while Pratt, who hails from Seattle, cheers on the Seattle Seahawks.

Both football fans and friends, Evans and Pratt made very public and very charitable bet: If the Patriots win, Pratt will don a Patriots jersey and make an appearance at Christopher's Haven, a non-profit organization that provides support housing for families whose children are receiving outpatient pediatric cancer treatments in Boston. If the Seahawks win, Evans will show up to Seattle Children's Hospital as Captain America, brandishing a 12th Man flag.

Check out their Twitter exchange below.

Well, well, well @prattprattpratt, looks like our teams are going into battle. For the next 2 weeks, you are not my friend, you are my enemy- Chris Evans (@ChrisEvans) January 19, 2015

@ChrisEvans We both know there's only one Captain America and his name is Russell Wilson. #SuperBowlBound #LOB #Repeat- chris pratt (@prattprattpratt) January 19, 2015

@prattprattpratt them's fightin words. Stakes? #whatisaseahawkanyway #somethingtombradyhunts- Chris Evans (@ChrisEvans) January 19, 2015

@ChrisEvans OK. Seahawks win you fly yourself to Seattle, visit @seattlechildren hospital as Captain America, waving the 12th man flag.- chris pratt (@prattprattpratt) January 21, 2015

@prattprattpratt I accept. And when the Patriots humiliate your seachickens, I expect Star-Lord to arrive at @chris_haven in a Brady jersey- Chris Evans (@ChrisEvans) January 21, 2015

Regardless of who wins the big game, fans and both charitable causes are the real winners here.